Figure 3.

Caspase activation in response to BMS-345541 and TRAIL. (a) Processing of caspase-8, -9 and -3, as well as of Bid was determined by western blotting in A-375, A-375-TS, MeWo and Mel2a treated with TRAIL (20 ng/ml) and/or BMS-345541 (A-375: 2 μM; other cells: 5 μM). (b) A-375 and A-375-TS were treated in addition to TRAIL and BMS-345541 with the pancaspase inhibitor zVAD-fmk (10 μM, 1 h pretreatment), and apoptosis (sub-G1 cells) was determined after 24 h (mean values and S.D.'s of two independent experiments, each with triplicates). Significant inhibition of apoptosis by zVAD-fmk is indicated (*P<0.05). (c) Expression of apoptosis regulators was determined by western blotting in A-375 and A-375-TS in response to BMS-345541±TRAIL (20 ng/ml) of 8 and 16 h of treatment. For the analysis of Mcl-1 and XIAP expression at 16 h, cells were treated in addition with the pancaspase inhibitor zVAD. (a–c) At least two independent experiments revealed comparable results