tinely cultured Idelalisib in Dulbeccos modified Eagles medium containing varying concentrations of foetal calf serum. All cells were used between passages six to nine. Cell proliferation assay Cells were seeded in triplicate at a concentration of 2. 5 104 ml, in 2 ml of complete medium in 6 well plates. After attachment, medium was replaced with serum poor medium, containing 2. 5% foetal calf serum in which the cells grew at a significantly reduced rate. Growth factors FGF 2 and EGF, and VEGF165 with and without the test compound at different concentrations was added and Inhibitors,Modulators,Libraries cells incubated for a further 72 h. Control wells were treated with 5 l DMSO. Concentration ranges of test compounds and pre incubation times were based on pilot studies.

MTT and immunofluorescence studies using active caspase 3 as a measure of apoptosis confirmed that test compounds were not cytotoxic at the concentrations used. After 72 h, cells were washed in PBS, detached in 0. 05%w v trypsin in PBS, and counted on a Coulter counter set to a threshold of 30 m. Experiments were performed at least twice Inhibitors,Modulators,Libraries in triplicate wells and significance was determined by the Student t test. A representative example is shown. a fresh 24 well plate in 0. 1% FCS and incubated with VEGF165 or the other growth factors and a range of concen trations of test compound for 24 h. Under these condi tions there was negligible proliferation but measurable migration. Slides were fixed in ethanol, stained with methylene blue and photographed. Inhibitors,Modulators,Libraries For each slide, 10 fields of view were counted at ran dom.

Each experiment was performed at least twice and significance was determined by the Student t test. Cell differentiation assays in Matrigel Inhibitors,Modulators,Libraries Cells were mixed with an equal volume of Matrigel at 4 C. Aliquots were added to the wells of a 48 well plate and allowed to polymerise when 500 l of microvascular endothelial cell medium contain ing VEGF165 or the other growth factors, with or without the test compound was added. The cells were incubated for 24 h at 37 C then fixed in 4% paraformaldehyde, washed in cold ethanol and air dried. Cells were stained with Geimsa, air dried and photo graphed. Ten random fields were selected and the number of closed tubes counted. All experiments were performed Inhibitors,Modulators,Libraries in triplicate and repeated at least twice and significance was determined by the Stu dent t test.

Chemoinvasion assay A Transwell cell culture chamber with 6. 5 mm diameter polycarbonate filters were coated with 30 g ml Matrigel. Cells were added to the upper chamber suspended in an appropriate medium. The medium containing free copy a range of concentrations of test com pound was added to the lower chamber in the presence and absence of VEGF165 or the other growth factors. After 24 h incubation at 37 C, the medium from the lower chamber was removed, cell fixed and stained.