Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It oxidizes 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] Detected in the liver and lung (at protein level). P450 can be induced to high levels in liver and other tissues by various foreign compounds, including drugs, pesticides, and carcinogens. Belongs to the cytochrome P450 family. CYP4B1 alleles