The retinoid X receptor and its ligands: versatile regulators of metabolic function, cell
differentiation and cell death Page 1 INTRODUCTION The concept of retinoids as a distinct
class of biological regulators has undergone profound changes over the last 20 years (for a
comprehensive review see (1). The original concept of retinoids as metabolites of vitamin A and
molecules with a chemical structure similar to all-trans-retinol was rooted in the origins of this
field of research in nutritional biochemistry and vision research. The discovery that many of the …