Reduction of caspase-9 in BLIN-4L. Cells were electroporated with the indicated concentrations of control (C) or caspase-9 (9) siRNA, allowed to recover for 3 days, and harvested for Western blotting as described in “Materials and methods.” Densitometric scanning showed that electroporation with 0.4, 4, 8, and 16 μM caspase-9 siRNA led to a reduction in caspase-9 protein of 71%, 78%, 86%, and 91%, respectively, when normalized to BID or caspase-2 as loading controls.