PTGS2 and pulmonary arterial hypertension: While the MCT-treated COX-2 KO mice developed mild PH with an average RVSP of 17mmHg, which was associated with only mild pulmonary artery muscularization, in the chronic hypoxia mouse model of PAH, both RVSP and RV hypertrophy were greater in the COX-2 KO than the WT mice [27].