GSTM2 and hepatocellular carcinoma: Interestingly, astaxanthin showed synergistic effects on the induction of the cellular glutathione level and the mRNA expression of Nrf2 and its target genes (NQO1, HO-1, and glutathione S-transferase mu 2 [GSTM2]) when combined with docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) in a human hepatoma cell line [23].