背景资料：This protein belongs to the aldehyde dehydrogenases family of proteins. It plays a role in a pathway of 9-cis-retinoic acid biosynthesis in vivo. This enzyme converts 9-cis-retinal into the retinoid X receptor ligand 9-cis-retinoic acid, and has approximately 40-fold higher activity with 9-cis-retinal than with all-trans-retinal. Therefore, it is the first known aldehyde dehydrogenase to show a preference for 9-cis-retinal relative to all-trans-retinal. Three transcript variants encoding distinct protein isoforms have been identified for this gene.