CYP1A2 and cancer: Cytochrome P450 1A2 (CYP1A2), as one of important CYP enzymes, is responsible for the metabolic activation of pro-carcinogens such as heterocyclic aromatic amines (HAA), polycyclic aromatic hydrocarbons (PAHs) and 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) and further contributes to the risk of cancer[2,3].