Gene Targeting of Retinoid Receptors

Gene targeting in embryonic stem (ES) cells is a powerful technique for the modification of the mouse genome (1 –3 ). Regarding the retinoid receptors, a number of laboratories have reported the phenotype of mice in which a given retinoic acid receptor (RAR) or retinoid X receptor (RXR) has been inactivated by this technique (14 –12 ). In addition, a number of cellular retinoid-binding protein-null mice have also been generated (13 –15 ).