The fluorescence of your released AMC was measured implementing an automated multiwell plate reader at excitation emission wavelengths of nm Measurement of GSH Total glutathione amounts had been measured through the approach to Tietze . Briefly, the cells had been washed with PBS, lysed in ml of . N perchloric acid for min at C. Glutathione information was measured in a P automatic reader from the addition of , dithio bis nitrobenzoic acid , nicotinamide adenine dinucleotide phosphate reduced tetrasodium salt and glutathione reductase . The reaction was monitored at nm for min Western blot analysis and detection of ubiquitinated proteins NB extracts for Western blot evaluation had been ready in ice cold extraction buffer consisting of mM Tris HCl , mM potassium acetate , mM dithiothreitol NP , mM EDTA, mM EGTA, mM PMSF, protease inhibitors cocktail plus a cocktail of phosphatase inhibitors . The samples were homogenized, centrifuged at C and protein content material determined through the BCA protein assay kit .
Complete protein was electrophoresed on SDS Web page gels and transferred to . mm nitrocellulose membranes , as described previously . Just after blocking, blots had been incubated overnight at C in nonfat dried milk with principal antibodies: anti a synuclein antibody , the chaperone anti Hsp ; anti p ; anti LC ; anti Atg ; anti tau and anti p tau . Other antibodies Wortmannin selleck and dilutions implemented from the research have been anti GSK a b , mouse anti GSKb and anti DJ . The levels of pERK protein involved in signaling of survival response pathways, have been measured by Western blot as outlined by previously described methods. We made use of amouse anti phospho ERK and rabbit anti ERK antibodies diluted and , respectively. To determine alterations in ubiquitination, NB cultures untreated or treated with epoxomicin and trehalose for h in defined medium with no serum, have been scraped in ml of lysis buffer and boiled for min. The lysates had been centrifuged at , g at C for min. mg of protein have been performed to immunoblot assay which has a rabbit polyclonal antibody to ubiquitin.
The secondary antibodies followed by ECL detection reagents had been used for immunodetection. Immunoblot of b actin diluted was carried out to show Avanafil selleck equal protein loading. The blots were quantified by home pc assisted video. Statistical analysis The outcomes have been statistically evaluated for significance with one particular way ANOVA followed by Newman Keuls many different comparison test. The interactions amongst the treatment options were analyzed by two way ANOVA followed by Bonferroni post check. Distinctions were regarded statistically substantial when p Examination of information was carried out applying the GraphPad PRISM software package Benefits Dose and time dependent results of trehalose over the autophagic pathway in human neuroblastoma NB cells Trehalose induces autophagy.

Our dataset is congeneric, but have numerous rotatable bonds, so we addressed a pharmacophore primarily based QSAR model. Pharmacophore primarily based QSAR versions were created for hypothesis employing the 35 member education set as well as a grid spacing of 1.0 A. QSAR versions containing one to 5 PLS aspects were produced, and also the designs were validated by predicting the exercise of test set ligands. three. Outcomes and discussion We begun our function reproducing the conformation of ABT 737 crystallized into 2YXJ. Analyzing the ligandereceptor interactions, it really is achievable to evidence principally hydrophobic contacts, but an oxygen from your SO2 moiety establishes a H bond with Gly138 and also the Score in area worth, which permits to calculate the docking power of a frozen conformation, is 8.08. ABT 737 was redocked in to the binding pocket and showed a comparable Score . The RMSD involving the two conformation was calculated by super positioning the heavy atoms: a value of one.
01 was obtained, using a greatest difference among the sulfur atom within the thiophenyl group . The higher reproducibility degree, of the crystallized conformation by docking, suggested to dock every one of the compounds current inside the dataset and to make use of the finest poses as starting up stage to produce the pharmacophore model. The docking success for ABT 737 , most beneficial Tivantinib distributor pose, are reported in Fig. 3b, together with those on the most lively derivatives within the tested series entry 32 and entry 39 . Structurally, these three compounds belong to the two aryl substituted N benzylpiperazine subclass, presenting a p chloro phenyl, a phenyl, and a biphenyl substituent respectively. It may be observed the substitution of chlorine atom does not determine a broad distinction while in the poses. As for ABT 737, while in the situation of BD 21441, an oxygen atomfrom SO2 moiety establishes a H bond with all the identical residue Gly138. Only within the case of the biphenyl moiety , the docking conformation is distinct.
In reality the presence of 3 consecutive aromatic rings bring about the rotation with the piperazine ring along with the creation of a H bond in between the NHt of dimethylamino moiety and the oxygen atom of Asn197. To uncover the prevalent pharmacophore hypothesis, the dataset was Cinacalcet divided into energetic and inactive sets . Molecules with pEC50 values increased than 7.00 had been thought to be to be energetic, and individuals with pEC50 values lower than 6.00 have been regarded as to be inactive, whereas individuals in in between had been regarded to become moderately lively. Fifty 1 five stage hypotheses have been recognized . Sixteen hypotheses survived towards the 3 various phases of PHASE scoring procedure , and so these were applied for that generation of QSAR models. For that QSAR models generation, non modeled molecules while in the dataset had been then aligned, based on matching with at least 3 pharmacophore features.

As a result, our outcomes displayed that Cin activated mutant p53, causing up expression of Bax, as well as triggering down expression of Bcl XL to promote apoptotic exercise in PLC PRF 5 cells. Prior examine has revealed the role of oxidative anxiety and the involvement of mitochondria in Cin mediated apoptosis in leukemia HL 60 cells . We discovered that after twelve 24 h of treatment, Cin induced cytochrome c release from mitochondria to the cytosol and trigerred the mitochondria apoptotic pathway. p53 is reported to mediate the up regulation of Bax , it really is possible that Cin mediated activation of cost-free radicals and toxic metabolites could activate mutant p53, top to a p53 dependent, and trigger caspase 3 activation and PARP cleavage. The release of mitochondrial cytochrome c in to the cytoplasm was reported to happen with caspase 3 activation and PARP degradation during the aloe emodin induced apoptosis of mutant p53 cells .
Latest proof signifies the MAPK loved ones protein kinases JNK and p38 are necessary mediators of apoptosis induced by various worry associated stimuli . The anxiety kinases are also activated by chemotherapy drugs, including betulinic acid, cisplatin, epigallocatechin 3 gallate and 2 methoxyestradiol . Yet, other reviews indicated that a distinctive Nilotinib purpose of ERK and phosphorylated ERK, from professional apoptotic to professional survival, which appears to rely on a host of parameters together with the cell form, drug dose, as well as status of other signal transduction pathways . In this examine, we demonstrated that activation of JNK, p38 and ERK promoted apoptosis by Cin treatment method in PLC PRF five cells. Soon after Cin treatment, the phosphorylation of JNK, ERK and p38 was pronounced, and appeared to be in the dose response method.
Organic compounds such as cinnamaldehyde, Quizartinib caffeic acid phenethyl ester and phenethyl isothiocyanate had been reported to activate and phosphorylate JNK, p38 and ERK . PFTa is capable to totally inhibit the modulation of Bcl 2 family members, and suppress the PARP cleavage in Cin taken care of cells, but not mutant p53. It has been reported that PFTa did not block mutant p53 expression on cervical carcinoma cells right after staurosporine therapy . PFTa, a modest molecule identified as an inhibitor of p53 transcriptional exercise, protects against the toxic uncomfortable side effects of anticancer remedy on the typical tissues; this suggests its likely for use in clinical research . It may possibly also interfere with apoptosis of tumor cells that sense DNA injury in response to genotoxic worry .
Our experiments obviously showed that PFTa substantially prevented Cin mediated apoptosis and blocked the expression of some apoptotic signal elements of PLC PRF 5 cells. MAPK inhibitors had been proven to modulate the phosphorylation of JNK, p38 and ERK . Interesting, remedy with JNK and ERK inhibitors significantly attenuated Cin induced cell death.

Cytokinins are a structurally diverse group of N substituted purine derivatives historically acknowledged as anti PCD hormones, principally since they promote growth and differentiation and delay senescence. Exclusively, their degree declines throughout senescence, and exogenous application of this hormone or overexpression from the bacterial CK biosynthetic enzyme isopentenyl transferase delays leaf senescence . Then again, such a view is lately challenged through the occurrence of CK induced PCD in suspension cells of a. thaliana, Daucus carota and Nicotiana tabacum . Adenine and adenosine derivatives with CK activities are also efficient apoptosis inducers in animal cells . On the total plant degree, toxicity related with large amounts of CKs in plant tissues has been reported episodically . In order to much better characterize the regulation of BI in plant cells, we screened for compounds that can modulate BI accumulation in the protein degree. We observed that cultured tobacco cells exogenously offered using the lively CK benzylaminopurine showed up regulation of NtBI .
In this paper, we describe the modulation in the NtBI protein underneath low and higher concentrations of CKs and we show a tight correlation concerning the accumulation from the protein along with the occurrence of the tension response. Furthermore, we present that CK induced cell death appears for being partially Cat dependent, while NtBI accumulation will not be Products and approaches Plant materials, culture conditions and treatments Unless of course otherwise specified, Vorinostat chemicals had been obtained from Sigma. CK habituated N. tabacum cv. Xanthi cells used in this research have already been in culture for at the very least 10 many years. Cells were subcultured weekly in Murashige and Skoog medium supplemented with sucrose and mM , dichlorophenoxyacetic acid . The day in the subculture is known as day , when subsequent days are referred to as days submit transfer . For treatment options, day previous cells were diluted : with fresh medium and employed days later on, so acquiring a homogenous exponentially expanding cell population equivalent to e DPT cells.
Thus, cells treated for h were equivalent to e DPT, when cells reach the stationary phase. When specified, CKs have been added towards the medium from a mM stock resolution, prepared by first dissolving the powder inside a drop of Dihydroartemisinin . M HCl . Control cells were treated with all the CK structural analog Ade at or mM. All pre treatments with LaCl, EGTA, CaCl, A or , bis ethane N,N,N,N tetraacetic acid have been performed for a period of min just before addition of benzylaminopurine . Within the case of LaCl and EGTA, toxicity related with these chemical substances was partially circumvented by the use of a quick treatment method while in the presence of the substantial Bap concentration.

The large temperature necessity serine protease HtrA Omi is usually a serine protease that promotes apoptosis by mechanisms similar to these attributed to Smac DIABLO . HtrA belongs to a loved ones of serine proteases which is effectively conserved from bacteria to people and isolated in mitochondria. It seems that Omi HtrA is involved in cellular strain responses, as it is upregulated after a heat shock or following endoplasmic reticulum anxiety, and because it could be induced through the antibiotic tunicamycin . Recently, in Omi HtrA mice, a neurodegenerative phenotype with qualities of Parkinson?s ailment was discovered, underscoring the relevance in the protease exercise of this protein within the brain not just beneath standard circumstances but additionally during the pathological state. The regarded protective anxiety response routines of bacterial Omi HtrA homologues as well as loss of proteolytic exercise in each mnd and Omi HtrA mice consequence in enhanced sensitivity to tension. This signifies that this protease may be vital for your transduction of mitochondria relevant anxiety signals in cells not committed to apoptosis .
On apoptosis, induced by utilizing staurosporine, TRAIL, or UV irradiation, HtrA is launched to the cytosol , the place the mature sort of the protein binds to IAPs inside a equivalent method as Smac DIABLO, therefore facilitating caspase activation . Notably, HtrA overexpression purmorphamine selleckchem can induce cell death during the presence of caspase inhibitors, as well as in Apaf and caspase cells . Mutation from the HtrA N terminus and simultaneous mutation of amino acid residues demanded for serine protease exercise fully abolished the death inducing perform of HtrA . So, HtrA promotes cell death via two several mechanisms: a single relies on IAP inhibition and includes a significant enhance of caspase action, whereas the other is determined by its serine protease action and it is caspase independent . Furthermore, HtrA Omi has also been implicated in mediating caspase independent cell death by means of its personal serine protease action. Omi HtrA is translocated from your mitochondria towards the cytosol in neurons immediately after focal ischemia in rats .
Interestingly, counteracting the proapoptotic agent Omi HtrA by UCF can be a novel route for neuroprotection underneath ischemic disorders. Therapeutic interventions that inhibit Omi HtrA expression, translocation, or protease action could produce an efficient strategy while in the treatment method of neurological ailments, during which apoptotic cell death plays an essential function IAPs a multifaceted switch for neuronal rescue Apoptosis taking place in neurological sickness PS-341 and stroke operates predominantly via the ??intrinsic mitochondrial pathway?? and will be counteracted by pro survival members of your Bcl family and by IAPs .

Also, from the heterozygous state it wants to become regarded as what the damaging implications of simultaneously silencing both mutant and wild sort genes are, since the consequences of this usually are not completely understood . An alternative tactic to prevent the accumulation of toxic proteins includes accelerating their degradation, which, if specifically targeted towards the mutant kind from the protein, could represent a beneficial and risk-free therapeutic method Mechanisms for clearance of polyglutamine proteins: the UPS and autophagy In eukaryotic cells, two principal pathways are essential for degradation of misfolded proteins: the ubiquitin proteasome technique and autophagy. Inside the former operation, the amino acid protein ubiquitin is conjugated to a lysine residue within the degradation bound substrate by means of the concerted actions of 3 enzymes: an activating enzyme , a conjugating enzyme , in addition to a ligase . Through this pathway, soluble, short lived proteins are targeted for the S proteasome, a multisubunit protease . Autophagy, on the flip side, won’t necessarily involve selective cargo recognition but it degrades long lived intracytoplasmic proteins and organelles by engulfment of portions of cytoplasm right into a double membrane vesicle termed the autophagosome.
The autophagosome then fuses using the lysosome and protein degradation takes place, as will be discussed in even more detail in Segment . Despite the fact that Htt is ubiquitinated and targeted for degradation from the proteasome, Venkatraman et al. and Holmberg GW9662 selleck chemicals et al. showed the polyglutamine tract can’t be efficiently cleaved by the catalytic subunit in the proteasome, so releasing an isolated polyglutamine tract from the proteasome, which could constitute an even more aggregate susceptible and toxic type. The UPS is usually a degradative pathway which is constitutively lively under normal ailments and hence it truly is problematic to discover mechanisms for improving its exercise. A short while ago, Lee et al. described a non catalytic method to boost proteasome action. They identified a smaller molecule that inhibited the deubiquitinating enzyme USP, involved in ubiquitin chain trimming.
Treatment with this particular compound enhanced degradation of proteins crucial in neurodegeneration this kind of as tau, TDP or ataxin , and could supply novel methods for improving protein degradation by regulating protein degradation by Rapamycin the UPS. Even so, improving degradation from the proteasome could possibly influence important brief lived proteins whose levels are tightly regulated, this kind of as p, and so may have deleterious effects. From the following sections, we will examine the autophagic machinery and how upregulation of autophagy may be helpful in HD and other polyglutamine diseases, at the same time as how autophagy homeostasis is compromised in these and other neurodegenerative diseases.

Additionally, an inhibition of Smac DIABLO perform , along with a cell protective effect on the caspase independent apoptosis inducing factor mediated cell death are actually described. Survivin was initially defined as being a so termed ??universal tumor associated antigen?? because it was identified to get extremely expressed within a good assortment of tumors . Having said that, beside its expression in neoplastic cells, Survivin can be detected in regular tissues and cells with large mitotic action . Even more studies using HeLa cells uncovered the mRNA of Survivin is upregulated at the G M transition with the cell cycle , and that Survivin is usually a shortlived protein which has a half existence time of roughly min . Inhibition of Survivin is related with cell cycle defects and disruption of its genetic locus leads to an embryonic lethal phenotype in homozygous mice which can be in line with its just recognized perform in the spindle checkpoint . Lately, even further functions of Survivin in proliferation and cell senescence have been described. Strong expression of Survivin is in a position to augment the release of Cdk from its inhibitor pinka, which facilitates the entry into S phase on the cell cycle .
Moreover, overexpressed Survivin was described to boost transcription of your gene for human telomere reverse transcriptase , postponing replicative senescence of cells. Most investigations revealed expression of Survivin protein in all phases with the cell cycle of tumor cells suggesting a deregulated expression pattern in these cells . In retrospective studies, individuals whose tumors overexpressed Survivin had a decreased SB-742457 total survival , a resistance to chemotherapy , and an elevated price of recurrence . Additionally, it’s been shown that for the duration of interphase transformed cells transport Survivin by CRM Exportin from the nucleus into the cytosol . This may well confer resistance to chemotherapy or radiotherapy and could contribute to a extra aggressive phenotype of tumors, whereas Survivin expression during the nucleus of tumor cells continues to be described to get a predictive of a favorable prognosis in gastric cancers, and lung cancer .
Considering a cytosolic localization enables its IAP perform we hypothesized that an enhanced nuclearexport of Survivin might be a mechanism of tumor cells to resist unfavorable situations, i.e. hypoxia, radiation, or chemotherapy. Conversely, current information recommend that nuclear Survivin influences the transcription of genes involved with advancement, senescence and apoptosis by an unknown mechanism PD0332991 resulting in phosphorylation and activation of transcription things like c myc and exact protein . So, we hypothesized that a predominant nuclear localization could influence the susceptibility to apoptosis by elevated transcription of professional apoptotic genes.

Celastrol inhibits the development of xenografted CML cells in nude mice The in vitro anti tumor activity of celastrol prompted us to examine if it would be beneficial against CML xenograft growth in nude mice. Toward this end, KBM or KBM TI cells were inoculated subcutaneously in nude mice. 5 days immediately after inoculation, when tumors became scalable , the mice had been randomized to get therapy with DMSO containing medium or celastrol for days. We and other folks have discovered this celastrol dosage for being well tolerated . According to the growth curves , celastrol significantly inhibited the development of both KBM and KBM TI tumors. The sizes and weights of tumors were drastically reduce while in the handled group than while in the management group . Immunohistochemical analysis utilizing antibody anti c Abl antibody indicated that c Abl immunoreactivity was inhibited while in the xenografts by celastrol remedy. Taken collectively, these data demonstrated in vivo anti tumor exercise of celastrol against CML cells irrespective of its TI mutation status, and inhibition of Bcr Abl expression occurred inside the xenografts immediately after celastrol treatment method.
In summary, our review showed that celastrol depleted Bcr Abl and potently inhibited the growth of CML cells expressing wild kind or TI Bcr Abl. We confirmed this activity with two pairs of CML cell lines Panobinostat . Celastrol inhibited the growth of imatinib resistant Bcr Abl TI also as imatinib sensitive CML cells in nude mouse xenografts. To our practical knowledge, this is the to start with report to show that celastrol is beneficial in vitro and in vivo against CML cells bearing TI Bcr Abl. Celastrol is among the main biological components purified from T. wilfordii. Hook. f. which is utilized in Chinese medication for hundreds of years to treat inflammation and antoimmune ailments . Hieronymus H et al. demonstrated that HSP inhibition represents a significant gene expression signature invoked by celastrol . Consistent with these preceding findings that celastrol lowers the protein amounts of customers such as Bcr Abl, Flt, and EGFR which are consumers of HSP , our findings exposed that celastrol induced lessen in Bcr Abl level and reduce in phosphorylation of downstream targets of Bcr Abl .
Provided that Bcr Abl is an addiction oncogene in CML cells, lowering Bcr Abl level and subsequently disabling its signaling may well outcome in growth inhibition and triggering from the intrinsic apoptosis pathway. It will likely be intriguing to exploit regardless if celastrol is successful during the mutant isoforms of Bcr Abl besides TI during the future function. It need to be mentioned that Chlorogenic acid reducing Bcr Abl may not be the sole mechanism responsible for the cytotoxic activity of celastrol. More mechanisms may improve the inhibitory result of celastrol. Our findings indicated that the levels of survivin, Mcl , and Akt have been decreased right after remedy with celastrol.

Falini and co staff have having said that questioned the oncogenic significance of EML ALK in NSCLC , because they had been capable to detect EML ALK transcripts by RT PCR in non neoplastic lung tissue from NSCLC patients, too as in lymphoid tissues. Additionally, in RT PCR positive lung tumours and standard lung tissue, presence within the transgene by FISH analysis was constrained to ca. within the complete cell population, and EML ALK protein was undetectable by IHC, Western Blotting, or immunoprecipitation. There is some degree of controversy concerning these findings , but as recommended by these authors themselves, it’s probably that significance of EML ALK in NSCLC will eventually be determined through ongoing clinical trials by using selective ALK inhibitors. Lung cancer is the major result in of cancer relevant death in the Usa and globally, and regardless of recent advancements in remedy within the ailment, the healthcare require remains extremely higher, with an total many years survival fee of . Clinical knowledge in NSCLC with EGFR inhibitors has demonstrated that treatment of picked patients bearing drug sensitive mutations is associated with strong clinical advantage . By analogy, and supported by the preclinical effects described above, lung tumours harbouring constitutively activated ALK could be expected to become responsive to clinical therapy with selective ALK inhibitors.
Although many smaller molecule inhibitors of ALK kinase activity are presently remaining characterized on the preclinical supplier Nafamostat level, to date only the dual c Met ALK inhibitor PF has reached clinical advancement. Preliminary clinical responses observed with this particular agent in NSCLC patients bearing ALK rearrangement shall be discussed under Inflammatory myofibroblastic tumour Chromosomal rearrangements involving the p locus have been described more than years ago as recurrent events in IMT, and had been subsequently identified to encode ALK fusion proteins . These tumours are of mesenchymal origin and therefore are composed of neoplastic spindle cells mixed having a reactive inflammatory infiltrate of lymphocytes and plasma cells. IMTs are unusual, which has a frequency of new situations annually in the United states of america. Surgical resection is normally the primary treatment method, but numerous cases build a alot more aggressive phenotype with occurrence of metastases.
IMTs are generally poorly responsive to typical chemotherapy. Approximately of scenarios are characterized through the presence of chromosomal rearrangement involving the short arm of chromosome , in which ALK is found. After the first identification of TPM ALK and TPM ALK chimeric Proteasome Inhibitors proteins in three IMT patients in , a series of extra fusion proteins have been detected including Cars ALK, CLTC ALK, ATIC ALK, RANBP ALK, SECLB ALK . Using the exception of RANPB ALK, which can be localized for the nuclear membrane, all of the other fusion proteins show a typical cytoplasmic staining. The expression of ALK was generally present in younger individuals and correlated with neighborhood recurrence rather then with distant metastasis formation.

PP absolutely inhibited mTORactivity inside of min, as judged by inhibition of phosphorylations of Thr and Ser of S kinase in Ras NIH T Mdr cells. As with S kinase, a reduce phosphorylation of E BP was observed in Ras NIH T Mdr cells. On the other hand, in Ras NIH T cells, lM PP induced a sustained inhibition of SK phosphorylation, and had restricted effects about the phosphorylation of E BP as time passes. More, remedy of U, an inhibitor of MEK ERK signaling pathway, induced partial resistance to PP induced mTOR inhibition. PP induces allosteric Beclin conformational adjust Due to the fact Bcl proteins inhibit autophagy by binding to the BH domain of Beclin , we up coming determined the direct results of PP over the interaction amongst Beclin and Bcl . Coimmunoprecipitation unveiled that PP induces the dissociation of your Beclin Bcl complicated . The conformational transform of Beclin was further proven by immunofluorescence microscopy . For this examine, we utilised a Beclin BH domain antibody that recognizes the exposed epitope of BH within the Beclin molecule. PP drastically increased the fluorescence intensity of Beclin BH domain antibody, but not that in the mouse antibody towards the whole Beclin protein.
These benefits imply that PP induces a conformational alter in Beclin in Ras NIH T cells, but not in Ras NIH T Mdr cells. In order to even further investigate the results of Beclin on PP induced cytotoxicity, we established secure Ras NIH T cell clones overexpressing Bcl by transfecting cells with pGFP Bcl . A single clone was picked, since it was identified to overexpress PARP Inhibitors Bcl over control level, as assessed by GFP expression . The cell viability of Ras NIH T Bcl was slightly greater than that of their parental cells soon after PP treatment method. Nevertheless, the simultaneous therapy of PP and MA led to a marked reduce of cell proliferation, indicating that MA may well synergistically augment the inhibitory action of ectopic Bcl about the induction of autophagy in Ras NIH T Bcl cells Discussion The acquisition of drug resistance by cancer cells is thought to account for your failure of countless anticancer therapies. Wehave developed a paclitaxel resistant Ras NIH T Mdr cell line by way of exposure to growing, sublethal concentrations of paclitaxel .
As with other chemotherapeutic medicines, paclitaxel resistance calls for a multidrugresistance phenotype mediated through the P glycoprotein efflux pump . On this study, we uncovered that Ras NIH T Mdr cells are extra vulnerable to Src inhibition in the course of PP remedy than are Ras NIH T cells. On the other hand, it will be unlikely the Metformin ability of PP to resensitize Ras NIH T Mdr cells is dependent on MDR function, for the reason that PP did not interfere with P glycoprotein function, as established by rhodamine assay. This suggests that P glycoprotein is simply not a major mechanism of chemotherapy sensitization by PP. George et al. also reported that Src inhibition restores paclitaxel sensitivity to paclitaxel resistant cancer cells by an MDRindependent mechanism.