These findings indicate that Bcl-xL inhibition by ABT-263 or ABT-737 can sensitize DTX-resistant prostate cancer cells to DTX, and they reveal a unique apoptotic pathway in which antagonism of Bcl-2 family members in caspase-9-inhibited prostate cancer cells triggers caspase-8-dependent apoptosis. Here, CASP9 is linked to prostate carcinoma.