The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and biosynthesis. Cytochrome P450 2E1 is induced by ethanol, diabetes and starvation. The enzyme metabolizes both endogenous substrates, such as ethanol, acetone, and acetal, and exogenous substrates including benzene, carbon tetrachloride, ethylene glycol, and nitrosamines. Due to its many substrates, this enzyme may be involved in such varied processes as gluconeogenesis, hepatic cirrhosis, diabetes, and cancer.