Histopathological features of PAH lesions—such as contractile phenotype, excessive ECM remodeling, and disturbed tissue architecture [22–24]—urged us to investigate whether there is a connection between BMPR2 deficiency and increased TGFβ signaling and how this relates to alterations in mechano-biology and ECM biology and EndMT. The gene discussed is TGFB1; the disease is pulmonary arterial hypertension.