Cell Death and Differentiation (2004) 11, S126–S143 & 2004 Nature Publishing Group All rights reserved 1350-9047/04 $30.00 www.nature.com/cdd Review Retinoid X receptors: X-ploring their (patho)physiological functions A Szanto1, V Narkar2, Q Shen2, IP Uray2, PJA Davies2 and aspects of metabolism. The discovery of retinoid receptors L Nagy*,1 substantially contributed to understanding how these small, lipophilic molecules, most importantly retinoic acid (RA), exert 1 Department of Biochemistry and Molecular Biology, Research Center for their pleiotropic effects.1,2 Retinoid receptors belong to the Molecular Medicine, University of Debrecen, Medical and Health Science family of nuclear hormone receptors, which includes steroid Center, Nagyerdei krt. 98, Debrecen H-4012, Hungary 2 hormone, thyroid hormone and vitamin D receptors, various Department of Integrative Biology and Pharmacology, The University of Texas- orphan receptors and also receptors activated by intermediary Houston Medical School, Houston, TX, USA * Corresponding author: L Nagy, Department of Biochemistry and Molecular metabolites: for example, peroxisome proliferator-activated Biology, University of Debrecen, Medical and Health Science Center, receptor (PPAR) by fatty acids, liver X receptor (LXR) by Nagyerdei krt. 98, Debrecen H-4012, Hungary. Tel: þ 36-52-416432; cholesterol metabolites, farnesoid X receptor (FXR) by bile Fax: þ 36-52-314989; E-mail:
[email protected] acids and pregnane X receptor (PXR) by xenobiotics.3,4 Members of this family function as ligand-activated