ABSTRACT
The endogenous production of perhaps three or more types of nuclear retinoid receptor ligands (RA, ddRA, and 9-cis-RA) raises the intriguing possibility that expression of vitamin A activity in the skin depends in on the relative concentrations of these ligands. How the endogenous ligands orchestrate the RARs in normal and diseased human keratinocytes in the absence or presence of synthetic retinoids remains to be established.
