Figure 6.

Caspase-9 is functionally relevant in etoposide-induced caspase-8 activation and apoptosis. A and B, cells were transfected with either caspase-9 or control siRNA. At 48 h after siRNA transfection, cells were treated with cisplatin (10 μg/ml) or etoposide (100 μg/ml). Caspase-9 expression was analyzed by Western blot 24 h after drug treatment (A). The DNA profiles were analyzed by LSC 24 h after drug treatment (B). The horizontal and vertical axes represent the DNA content and cell number, respectively. Apoptotic cell population is indicated as a percentage of the sub-G₁ fraction. The cleavage of procaspase-9 and Bid was analyzed by Western blot with caspases-9 and Bid antibodies 24 h after drug treatment (C). β-actin was used as a loading control.