CYP2E1 is a cytochrome P450 monooxygenase primarily involved in metabolizing fatty acids and xenobiotics. Mechanistically, it catalyzes hydroxylation of carbon-hydrogen bonds by inserting one oxygen atom into substrates while reducing the second to water, using electrons from NADPH via cytochrome P450 reductase 12. CYP2E1 displays highest catalytic activity for saturated fatty acids, specifically hydroxylating at the omega-1 position 12. The enzyme also metabolizes ethanol to acetaldehyde and activates xenobiotics including polychlorinated biphenyls 34. CYP2E1 is predominantly hepatic but shows tissue-specific expression patterns, with catalytically active forms detected only in tissues expressing the 1.8 kb transcript 5. Functionally, mitochondrially-localized CYP2E1 generates reactive oxygen species (ROS) that drives alcohol-induced hepatotoxicity and hepatic steatosis through mitochondrial dysfunction and retrograde signaling 3. Clinically, CYP2E1 downregulation is associated with hepatocellular carcinoma, particularly in chr10 hepatitis B virus infection, where viral HBx protein inhibits CYP2E1 expression via hepatocyte nuclear factor 4α 6. CYP2E1 expression is regulated by environmental factors including ethanol and dietary components 78.