Our data revealed significant down-regulation of EC markers such as desmoplakin and four different cytokeratins (KRT7, 8, 18 and 80) and up-regulation of mesenchymal markers α-SMA, BMP4 and TGF-β2 in PAH-HPMEC cells compared to controls. The gene discussed is ACTA1; the disease is pulmonary arterial hypertension.