TP53 and malignant colon neoplasm: Furthermore, inhibition of caspase-3 activity by the use of caspase-3 inhibitor Z-VAD-fmk caused a significant (p < 0.05) increase in cell viability of both HCT-116 p53 +/+ and HCT-116 p53 −/− colon cancer cells, which suggest the involvement of caspase-3 in MSM-induced apoptosis.