TGFB1 and pulmonary arterial hypertension: In addition, BMPR2 is located in the cell membrane caveolae and interacts directly with the caveolin-1 in different cellular types, consisting of smooth muscle cells of vessels; therefore, the mutations in CAV1 may also cause PAH by interfering with TGF-β signaling (Hartung et al., 2006; Wertz and Bauer, 2008).