NQO1 and hepatocellular carcinoma: For instance, TCDD induces NQO1 gene expression in human hepatoma cell lines, but antioxidant N-acetyl cysteine (NAC) or CYP1A1 siRNA decreases NQO1 gene induction, indicating that NQO1 induction is controlled by CYP1A1 activity through oxidative stress [18].