Here, we compared preclinical and clinical PAH drug candidates, including DAPT (γ-secretase inhibitor) [27], riociguat [28], sildenafil [29], and L-902,688, and showed that L-902,688 prevented TGF-β1-induced EndMT, which is characterized by an increase in mesenchymal and EndMT markers such as Twist and α-SMA. The gene discussed is TGFB1; the disease is pulmonary arterial hypertension.