Figure 2: Western blotting to examine activation of receptor-mediated caspase cascade for apoptosis. Treatments (7 days): CTL, ATRA (1.5 µg/kg/day), IFN-γ (5000 units/kg/day), and ATRA (1.5 µg/kg/day) plus 4 h later IFN-γ (5000 units/kg/day). Representative Western blots show levels of 42 kD β-actin, 20 kD caspase-8 active fragments, and 15 kD tBid. Activation of caspase-8 caused cleavage of Bid to tBid for translocation to mitochondria to promote mitochondria-mediated activation of the caspases leading to apoptosis in T98G xenograft.