TGFB1 and pulmonary arterial hypertension: Upregulation of miR-199a-5p has been reported in the lung tissue from mouse and rat models of pulmonary artery hypertension (PAH), which also identified SMAD3 (which plays a key role in transmitting TGF-β signals from cell surface receptors to the nucleus) as a target gene of miR-199a-5p [10].