ADH7(Alcohol dehydrogenase class 4 mu/sigma chain) is also named as gastric alcohol dehydrogenase, retinol dehydrogenase and belongs to the zinc-containing alcohol dehydrogenase family. The ubiquitous expression pattern of ADH7 during embryogenesis has led to the notion that the enzymatic conversion of retinol to retinal occurs more or less uniformly and plays no role in the spatial or temporal regulation of RA synthesis during embryonic development.