Carbonyl reductase 3(CBR3) is one of several monomeric NADPH-dependent oxidoreductases. This protein catalyzes the reduction of a large number of biologically and pharmacologically active carbonyl compounds to their corresponding alcohols. It also contains three exons spanning 11.2 kilobases and is closely linked to another carbonyl reductase gene - CBR1. Some studies suggest that it mediates 9-cis-retinoic acid-induced cytostatis and is a potential prognostic marker for oral malignancy.