In this model, fibroblast-specific expression of a dominant negative, kinase-deficient TGFβR2 variant paradoxically results in constitutive overexpression of TGF-β1 ligand and strongly increased basal TGF-β superfamily signaling, leading to spontaneous development of fibrosis and PAH with age. The gene discussed is TGFBR2; the disease is pulmonary arterial hypertension.