HO enzymes are known to be crucial components of the cellular antioxidant system and to be involved in various diseases, including ischemic stroke (Panahian et al., 1999), and HO-1 induction by activated Nrf2 (Qiang et al., 2004) protects cells against oxidative stress (de Vries et al., 2008). The gene discussed is HMOX1; the disease is ischemic stroke.