CYP2D6 and neoplasm: In Dark-Agouti (DA) male and female rats, considered to be extensive and poor debrisoquine (CYP2D6 substrate) metabolizers respectively, male DA rats were the most susceptible to OTA-induced tumorigenesis, while DA females were resistant (Table 1); thus, OTA tumor susceptibility was related to CYP2D6 metabolism [35].