“…Experiments with these new models (Cyp2c, Cyp2d, and Cyp3a KO mice) are clarifying the roles for enzyme families in the metabolism of xenobiotics. Presently, we used these three lines of KO mice to study two P450-related problems: (1) assessing possible mechanistic roles for CYP2C, CYP2D, and/or CYP3A subfamilies in the pain-relieving actions of morphine, and (2) , Taconic 9177-M) contain homozygous deletions of 14 full-length P450 genes (Cyp2c55, Cyp2c65, Cyp2c66, Cyp2c29, Cyp2c38, Cyp2c39, Cyp2c67, Cyp2c68, Cyp2c40, Cyp2c69, Cyp2c37, Cyp2c54, Cyp2c50, and Cyp2c70), but retain a functional Cyp2c44 (Scheer et al, 2012a). Cyp2d KOs [C57BL/6-Del(15Cyp2d22-Cyp2d26)1Arte, Taconic 9178-M] contain homozygous deletions of nine full-length P450 genes (Cyp2d22, Cyp2d11, Cyp2d10, Cyp2d9, Cyp2d12, Cyp2d34, Cyp2d13, Cyp2d40, and Cyp2d26) as recently described (Scheer et al, 2012b).…”