Using NADP+ as cofactor, several members of the short-chain dehydrogenases/reductases (SDR) family can (reversibly) catalyse the oxidation of 11-cis-retinol (11cROL) to 11-cis-retinal (11cRAL) in retinal pigment epithelium (RPE) cells. Retinol dehydrogenases 10 and 11 (RDH10 and 11) are two such members utilizing the cofactor NADP+ (Wu et al. 2002, Kedishvili et al. 2002 respectively). Cellular retinaldehyde-binding protein (RLBP1), the protein bound to 11cRAL in RPE, is not present in photoreceptor cells.