The cytochrome P450 mixed function oxidase system plays a major role in the metabolism of important endogenous substrates such as in cholesterol biosynthesis and cholesterol conversion to bile acids, formation of steroid hormones, androgens and estrogens, metabolism of vitamin D3 to the active 1,25-dihydroxyvitamin D3, omega hydroxylation of fatty acids, as well as biotransformation of exogenous xenobiotics.