The latter one, a ligand of the aryl hydrocarbon receptor, was found to repress the expression of the CYP1A1 (aryl hydrocarbon hydroxylase) gene in hepatoma cells by targeting DNA methyltransferase 3A, which led to impairment of the cellular detoxification system [7,8,9,10]. This evidence concerns the gene CYP1A1 and hepatocellular carcinoma.