TP53 and hepatocellular carcinoma: These results suggest that: (1) different modes of p21WAF1/CIP1regulation are involved in HCCs differing in their hepatitis viral infection status, and p21WAF1/CIP1expression appears to be predominantly related to altered p53 in HCV-related HCCs; (2) disruption of the p53–p21WAF1/CIP1cell- cycle-regulating pathway may contribute to malignant progression of HCC.