Inhibition of caspases does not block DTX-induced cytotoxicity in PC3 cells. A. Percentage of surviving PC3 cells treated with DTX in the presence and absence of Z-VAD-FMK, AC-VDVAD-CHO, or both inhibitors. Cells were pre-treated with the inhibitors 1 h before exposure to DTX. Cell viability was determined by crystal violet staining. Absorbance was measured at 570 nm and the values were normalized against those of untreated cells, which were assumed to be 100% viable. Errors bars represent the standard deviation of at least three independent experiments done in triplicate (*p < 0.05 compared to untreated, t-test): B. Same as in panel A except that cell viability was measured using the MTT assay. Errors bars represent the standard deviation of two independent experiments done in hexuplicates (*p < 0.05 compared to untreated, t-test): C. Morphological analysis of PC3 cells treated as indicated above for 48 h. Cells were visualized on an Olympus IX70 inverted microscope equipped with Hoffmann Modulation Contrast.