SMAD9 and heritable pulmonary arterial hypertension: Several lung- and blood-derived cells of HPAH patients bearing either BMPR2 (W9X (TGA-C), R213X (TGA-T), R321X (TGA-G), R332X (TGA-G), Q433X (TAG-A), and (E845X (TAA-A)) or SMAD9 (R294X (TGA-A)) nonsense mutations were analyzed.