HMOX1 and cancer: The studies found and identified Nrf2 as a major regulator of chemoresistance in cancer stem cell (CSC)-enriched breast cancers (Achuthan et al., 2011; Ryoo et al., 2015) as well as the activation of Nrf2-associated antioxidant genes such as HO-1, NQO1, Prx1, and others that leads to radioresistance in several other cancer cells (Zhou et al., 2013).