HNF4A and hepatocellular carcinoma: While P1-HNF4α normally represses cell cycle and epithelial-to-mesenchymal transition (EMT) genes in a circadian manner, P2-HNF4α is selectively induced in HCC, where it directly inhibits the expression of the circadian protein BMAL1 and leads to the cytoplasmic expression of the P1 isoform.