Discusses the study which analyzed the crystal structure of ligand-binding domain (LBD) of human retinoid receptor, RXR-alpha for 9-cis retinoic acid. Dimeric packing of fold of anatiparallel alpha-helical sandwich; Homodimerization of RXR-alpha and LBD; Interaction of 9-cis retinoic acid with transactivation function AF-2; Prototype structure of fold.