Cytochromes P450 are a group of heme-thiolate monooxygenases. They oxidize a variety of structurally unrelated compounds, including steroids, fatty acids, and xenobiotics. an organic molecule + O2 + reduced [NADPH--hemoprotein reductase] = an alcohol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Expressed in induced liver, kidney, gill and gut. Weakly expressed in control liver. By 3-methylcholanthrene (3MC). Belongs to the cytochrome P450 family.