Fig. 5. Apoptin activates caspase-3 but not caspase-8. Western blot analysis of cell lysates from Jurkat cells treated with apoptin in the presence or absence of a caspase inhibitor zVAD-fmk (40 µM) for 0, 48 and 60 hours to detect the levels of caspase-3 and caspase-8, and cleavage. Jurkat cells treated with TAT-GFP are shown as a control. The molecular sizes of pro-caspase molecules and the active fragments are indicated.