Figure 3.
Caspase-8 contributes to activation of the intrinsic apoptosis pathway upon treatment with ABT-737 and TRAIL. (a) U87MG (left panel) and U118MG (right panel) cells were treated for 4 h with 5 ng/ml (U87MG) or 10 ng/ml (U118MG) TRAIL and 5 μM ABT-737 in the presence or absence of 20 μM caspase-8 inhibitor (zIETD.fmk). Bax conformational change was determined by immunoprecipitation (IP); Bax expression in lysates served as control. (b) U87MG (left panel) and U118MG (right panel) cells were treated for 6 h with 5 ng/ml (U87MG) or 10 ng/ml (U118MG) TRAIL and 5 μM ABT-737 in the presence or absence of 20 μM caspase-8 inhibitor (zIETD.fmk). Mitochondrial transmembrane potential was assessed by FACS analysis. The percentage of cells with loss of mitochondrial potential with mean+S.E.M. of three independent experiments carried out in triplicate is shown (*P<0.005)