HMOX1 and hepatocellular carcinoma: For example, microcystin increases the Nrf2-target genes Nqo1 and Ho-1 in NIH3T3 cells and HepG2 cells [7], and addition of microcystin to hepatoma HepG2 and Hep3B cells results in microcystin uptake into hepatocytes and the release of Nrf2 into the nucleus [23].