Control of gene expression by novel metabolic intermediates.

In view of the recent discoveries of novel nuclear receptors (NRs) whose ligands remain to be determined, metabolic intermediates may be considered as ligands for these receptors and undiscovered or overlooked intermediates may play important roles in regulating gene expression by activating or repressing the action of these nuclear receptors. This article is part of a Special Issue entitled 'Steroid Perspectives'.