HMOX1 and cancer: The nuclear factor E2-related factor 2 (NRF2) target genes heme oxygenase (decycling) 1 (HMOX1), NAD(P)H:quinone oxidoreductase (NQO) 1 and glutamate-cysteine ligase (GCL) M were up-regulated whereas glutathione peroxidase (GPX) 1 and other selenoprotein genes (SEPW1, SEPN1 or SEPP1) were down-regulated in both cancer cells and normal cells (Fig. 6d, Additional file 1: Figure S4).