The RXRA gene at 9q34.2 codes for retinoic acid receptor RXR-alpha which has at least two expressed isoforms. This is the receptor for retinoic acid (all-trans or preferably 9-cis retinoic acid) and binds as a heterodimer to its target response element after ligand binding. This allows regulation of gene expression in several biological processes. The retinoic acid response elements (RARE) are made up of tandem 5'-AGGTCA-3' sites known as DR1-DR5. The thyroid hormone, vitamin D , and retinoid X receptors all share a similar response element. RXR-alpha is a common heterodimeric partner for a number of nuclear receptors such as those involved in fatty acid metabolism which associate with a multiprotein complex containing transcription corepressors that induce histone acetylation, chromatin condensation and transcriptional suppression.