FIG. 4.

Inhibition of caspase-9 activity does not delay apoptosis induction by the rM51R-M virus. L929 cells that overexpress Bcl-2- (L929-Bcl-2) or an empty vector control (L929-Bcl-2-EV) were generated. (A) Cell lysates were generated and analyzed via Western blotting as described in the legend to Fig. 3, using an antibody against Bcl-2. (B and C) L929-Bcl-2 and L929-Bcl-2-EV cells were mock infected (M) or infected with rM51R-M virus. At the indicated times postinfection, cell lysates were obtained and analyzed via Western blotting as described above, utilizing an antibody against caspase-9. A representative gel is depicted in panel B. Panel C shows quantitation of procaspase-9 expression at 4 (black bars), 8 (hatched bars), and 16 (white bars) h postinfection. These values are normalized to actin protein expression and are shown as percentages of mock-infected samples. The data represent the averages ± SEM from three experiments. hpi, hours postinfection; *, P is <0.01 relative to mock-infected L929-Bcl-2-EV cells. (D) L929-Bcl-2 cells (open symbols) and L929-Bcl-2-EV cells (filled symbols) were infected with the rM51R-M virus (squares) or treated with 1 μM SSP (circles). Cells entering apoptosis were monitored by time-lapse video microscopy as described in the legend to Fig. 1. The data represent the averages ± SEM from three experiments.