HMOX1 and pulmonary arterial hypertension: Although Hmox1 is downregulated in the RV of a porcine systemic-to-pulmonary shunt model of PAH (Belhaj et al., 2013), Hmox1 is upregulated in the RV and lungs in response to high dose MCT treatment in mice (600 mg/kg), and inhibition of Hmox1 using a specific inhibitor of Hmox1, SnPP IX in these animals actually leads to a promotion of inflammatory changes in the lung and increased RV hypertrophy.