Combined cisplatin and bortezomib treatment enhances casp-3, -8 and -9 activity. (A) Expression levels of effector casp-3 protein, determined by ELISA. Values are expressed as the mean ± standard deviation of triplicate experiments. (B) Expression levels of initiator apoptotic caspases, detected by western blotting. Casp, caspase; C, control; cis, cisplatin; Bor, bortezomib.