Cytochrome P450 2E1, a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body. While it is only involved in the oxidative metabolism of a small range of substrates, there are some important drug interactions mediated by CYP2E1. CYP2E1 - CYP2E1 Ligands. While it is involved only in the oxidative metabolism of a small range of substrates, there are many important drug interactions mediated by CYP2E1.Within one day of birth, the rat hepatic CYP2E1 gene is activated transcriptionally. CYP2E1 expression is easily inducible. It seems that there exist two stages of induction, a posttranslational mechanism for increased protein stability at low levels of ethanol, and an additional transciptional induction at high levels of ethanol.