Although yet to be established in cancer, biliverdin/bilirubin has been demonstrated to also play a cytoprotective role, decreasing nitric oxide (NO) production by inhibiting iNOS expression (Figure 3) (96, 97) and mediating anti-apoptotic effects through the ERK1/2 pathway during hypoxia (98) in non-cancer models. The gene discussed is MAPK3; the disease is cancer.