Transcriptional regulator which controls the expression of hepatic genes during the transition of endodermal cells to hepatic progenitor cells, facilitating the recruitment of RNA pol II to the promoters of target genes (PubMed:30597922). Activates the transcription of CYP2C38 (By similarity). Represses the CLOCK-BMAL1 transcriptional activity and is essential for circadian rhythm maintenance and period regulation in the liver and colon cells (PubMed:30530698). {ECO:0000250|UniProtKB:P49698, ECO:0000269|PubMed:30530698, ECO:0000269|PubMed:30597922}. This is the function of Ensembl gene identifier ENSG00000101076 (HNF4A, hepatocyte nuclear factor 4 alpha).