At different time points of cisplatin exposure, RPTC cytosol was isolated as described under “Experimental Procedures” and protein levels of cyto-chrome c and active caspase 3 (17–19-kDa cleaved fragment) determined by immunoblotting. A, the effect of cisplatin exposure on the release of cytochrome c to the RPTC cytosol. B, the effect of cisplatin on caspase-3 cleavage in RPTC. C, the effect of ERK1/2 inhibition (50 μm PD98059) on caspase-3 cleavage during cisplatin exposure in RPTC. D, the effect of PKC-α inhibition (10 nm Go6976) on caspase-3 cleavage during cisplatin exposure in RPTC. Experiments were performed three times with comparable results.