TP53 and colonic neoplasm: However, it has been shown that, nitric oxide (NO), which is induced by inflammatory cytokines such as TNF-α a and IFN-γ in chronic hepatitis C virus (HCV) infection, can induce mutation of cancer-related genes including the p53. In cases of colon cancer and lung cancer, nitric oxide synthetase 2 activity in the tumor closely related to the G:C to A:T mutations in the p53 gene within the CpG sites [11], which is the major type of mutation in the p53 gene found in HCC without AFB1 contamination.