Figure 3. Caspase-9 function is normal and Apaf-1 function is abnormal in chemoresistant cells.

A. S100 cytosolic lysates from A2780 ovarian cancer cells immunodepleted of caspase-9 (A2780 IP C9), A2780, OVCA 429, and SKOV3 cells alone, or mixed in a 1:1 ratio as indicated. Caspase-9 function was assayed by incubating extracts with in vitro translated [³⁵S] pro-caspase-3 in the presence or absence of cytochrome c/dATP. After 30 minutes of incubation, ³⁵S-pro-caspase-3 and its cleavage products, p19/17, were separated by SDS-PAGE. Gels were dried and exposed for autoradiography. B. S100 cytosolic lysates from wt MEF, MEF Apaf-1 −/−, A2780, OVCA 429, or SKOV3 cells were prepared. Apoptosome function was assayed as indicated in (A). C. Cytosolic lysates from wt MEF were mixed in a 1: 1 ratio with MEF Apaf-1 −/−, A2780, OVCA 429, or SKOV3 cells, and apoptosome function was tested as indicated in (A). D. Cytosolic lysates from MEF Apaf-1 −/− were mixed in a 1: 1 ratio with wt MEF, A2780, OVCA 429, or SKOV3 cells, and apoptosome function was tested as indicated in (A).