It has been widely recognized by in uivo studies that the vitamin A has many physiolosical roles such as on the visual cycle, growth, reproduction, normal development, and the maintenance of some epithelial tissues. However, the mechanisms of those functions at the molecular level are still remained obscure, except on the vision which has been elucidated in some detail. In the past ten years, a variety of vitamin A binding proteins were found in several tissues, and their functions particularly on the roles of transportation system of the vitamin have been studied in animal. Furthermore, the recent topics of great interest were isolations of specific nuclear receptors for retinoic acid from some animal tissues. In this review, the author briefly described the recent advancement of vitamin A researchs.
