Retinoids, a group of natural and synthetic analogues of vitamin A (retinol), modulate the differentiation of many cell types. Retinoids are also used for the prevention and treatment of cancer. The actions of retinoids are generally mediated by the retinoic acid receptors (RARs A, B, and ;) and the retinoid X receptors (RXRs A, B, and ;). One of the RARs, RARB, is expressed at reduced levels i...