Inhibition of apoptosis and PARP cleavage by the caspase inhibitor z-VAD in NB4 cells. NB4 cells (300,000/mL) were treated for 6 hours with vehicle (DMSO, Control) or with 10−6 mol/L CD437 following pretreatment for 2 hours in the presence or absence of the indicated concentration of z-VAD. (A) Dashed columns indicate the percentage of viable cells (erythrosin staining), whereas solid columns indicate the percentage of apoptotic cells (DAPI staining). Results are the mean ± SD of three separate culture dishes. (B) Extracts from cells treated as in (A) were subjected to Western blot analysis using an anti-PARP–specific antibody. Filters were reprobed with actin to ensure that similar amounts of protein were loaded in each lane. Arrowheads on the right indicate the position of the PARP intact protein and one of its proteolytic fragments. The molecular weight of protein standards is indicated on the left. The results were replicated in a separate experiment.
