ADH1 and ADH4 are the major alcohol dehydrogenases (ADH) in ethanol and retinol oxidation. ADH activity and protein expression were investigated in rat gastrointestinal tissuehomogenates by enzymatic andWesternblot analyses. In addition, sections of adult rat gastrointestinal tract were examined byin situ hybridization and thewhole tract, changing their localization and relative content as a function of the area studied.