BMPR2 and heritable pulmonary arterial hypertension: The feature of PH is intense remodeling of small pulmonary arteries by myofibroblast and smooth muscle cell proliferation, and for familial pulmonary arterial hypertension, the bone morphogenetic protein type II receptor (BMPR-II) mutation in pulmonary artery smooth muscle cells contributes to abnormal growth responses to the transforming growth factor (TGF)-beta/bone morphogenetic protein (BMP) [5].