CDKN1A and hepatocellular carcinoma: Several groups studying expression of p21WAF1/CIP1 in human hepatocellular carcinoma have documented that there were reduced p21WAF1/CIP1 mRNA and protein levels in human HCC (Hui et al, 1997; Naka et al, 1998; Qin et al, 1998; Shi et al, 2000).