The function of NR1I2 (nuclear receptor subfamily 1 group I member 2, Ensembl gene identifier ENSG00000144852) is as follows. Nuclear receptor that acts as a transcription factor regulating genes involved in the metabolism and excretion of xenobiotics, drugs, and endogenous compounds. Activated by a broad range of endogenous steroids (e.g. pregnenolone, progesterone) and xenobiotics, including the antibiotic rifampicin and certain plant- derived metabolites. Upon ligand binding, translocates to the nucleus, forms a heterodimer with the retinoid X receptor/RXR, and binds to response elements in target promoters, leading to transcriptional activation. Target genes include cytochrome P450 enzymes such as CYP3A4 and ATP-binding cassette transporters including ABCB1/MDR1. {ECO:0000269|PubMed:11297522, ECO:0000269|PubMed:11668216, ECO:0000269|PubMed:12578355, ECO:0000269|PubMed:18768384, ECO:0000269|PubMed:19297428, ECO:0000269|PubMed:26534988, ECO:0000269|PubMed:9727070}.