Fig. 7. Activation of caspase-8 and -10 in PMA-induced apoptosis. (A) TF-1 cells were treated with PMA for different time intervals (0-12 hours). Whole cell lysates (50 µg) were resolved by SDS-PAGE followed by immunoblotting with antibodies specific for caspase-8 and caspase-10. (B) TF-1 cells were pre-incubated with different caspase inhibitors (5 µM) for 30 minutes as indicated prior to PMA treatment. The corresponding inhibitor of each caspase is z-DEVD-fmk for caspase-3, z-IETD-fmk for caspase-8, z-LEHD-fmk for caspase-9 and z-AEVD-fmk for caspase-10. After 8 hours, cells were analyzed for caspase-3 activity as described in the legend to Fig. 4. (C) Following pretreatment with z-DEVD-fmk (10 or 50 µM) for 30 minutes, TF-1 cells were treated with PMA for 9 hours and harvested for immunoblot analysis using antibodies specific for ROCKI, caspase-8 and -10.