Usual human livers contain two major ALDH isozymes, i.e., cytosolic ALDH1 and mitochondrial ALDH2(1). Human red cell aldehyde dehydrogenase (ALDH) resembles the liver cytosolic isozyme in numerous physicochemical properties. Thus, the erythrocyte enzyme, by virtue of its chemical and structural identity with the liver cytosolic enzyme, may serve as a suitable peripheral enzyme model to understand the cause and mechanism of alcohol abuse-related changes in liver cytosolic ALDH that has been found to be reduced in alcoholics (2). ALDH1A1 is known to catalyze the oxidation of retinaldehyde to retinoic acid. Overexpression of human ALDH1A1 in HEK cells led to a more than 20-fold increase in 3-deoxyglucosone dehydrogenase activity (3).