text: We found that reduction of the carcinogenic hydroxylamines of the aromatic amine << 4-aminobiphenyl >> (4-ABP; found in cigarette smoke) and the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP; found in grilled meats) was indeed catalyzed by a purified system containing only [[ human b5R ]] and cyt b5.