Three highly purified forms of cytochrome P-450 (P-450a, P-450b, P-450c) from Aroclor 1254-induced rat hepatic microsomes catalyzed the monooxygenation of 1-(2- chloroethyl)-3-(trans-4-methylcyclohexyl)-1-nitrosourea (MeCCNU) and 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea (CCNU) in the presence of purified NADPH cytochrome P-450 reductase, NADPH and oxygen. Cytochrome P -450- dependent monooxygenation of CCNU gave six alicyclic hydroxylation products...