Cytochrome c and dATP-dependent caspase activation promotes proteolysis of apoptotic substrates. Cell-free reactions were prepared as described in the legend to Fig 2. At the indicated times, portions (50 μg protein) of the extract were removed for Western blotting with antibodies against PKCδ (A), gelsolin (B), or fodrin (C). Molecular weights (kD) are listed for the endogenous and cleaved forms.