CTNNB1 and hepatocellular carcinoma: Somatic mutations of CTNNB1, encoding β-catenin, are most frequently identified in HCC, and accumulated in exon 3 (amino acid position 5–80) corresponding to the serine/threonine (Ser/Thr) phosphorylation site for GSK3β which normally promotes ubiquitination and degradation of β-catenin.