The transcriptional regulation displayed by all-trans-retinoic acid (RA) and 9-cis-RA is mediated by their nuclear receptors, RARs and RXRs, which selectively form heterodimers in presence of a naturally occurring RA response element, βRARE. By a standardized procedure involving Superose-12 size-exclusion column chromatography, we have resolved RAR α - RXR α complex in the presence βRARE and evaluated the optimal conditions for the heterodimer formation. It has been known that cellular retinoic acid-binding protein II is involved in the direct channeling of RA to RARs. We made attempts to detect a stable binding protein complex with RAR-RXR dimer that is resolvable by Superose-12 chromatography. The chromatographic resolution patterns revealed that such a stable association was not noticeable, probably because the potential receptor heterodimer-binding protein complex is short-lived, and perhaps is a transiently formed intermediate.