FIG. 7.

Inhibition of caspase-8 activity inhibits activation of caspase-9 but not caspase-12. L929 cells were left untreated or pretreated for 1 h with 10 μM Z-IETD-CHO and then mock infected (M) or infected with the rM51R-M virus. At the indicated times postinfection, cell lysates were prepared and analyzed via Western blotting as described in the legend to Fig. 3, utilizing antibodies against caspase-9 (A and B) and caspase-12 (C and D). Representative gels are depicted in panels A and C. Panels B and D show quantitation of procaspase protein expression at 4 (black bars), 8 (hatched bars), and 16 (white bars) h postinfection. These values are normalized to actin protein expression and are presented as percentages of mock-infected samples. The data represent the averages ± SEM from four experiments. (B and D) hpi, hours postinfection; *, P is <0.05 relative to untreated, mock-infected L929 cells; **, P is <0.05 relative to Z-IETD-CHO- pretreated L929 cells at 8 h postinfection.