Altered TGF-β family signaling underlies many forms of pulmonary hypertension (PH), as evidenced by mutations in TGF-β pathway members underlying heritable PH; increased TGF-β signaling present in human and animal PH model lung tissue; and excessive activation of latent TGF-β26. The gene discussed is TGFB1; the disease is pulmonary arterial hypertension.