TGFB1 and pulmonary arterial hypertension: To the best of our knowledge, these findings are the first to identify and compare with preclinical and clinical PAH drug candidates such as PTU [26], DATP [27], riociguat [28], and sildenafil [29], regarding the preventative effect of TGF-β1-induced EndMT in vitro relative to combination therapies for PAH.