The result demonstrated that the protein expressions of Snail, Zeb1, fibronectin, Vimentin, TGF‐ß, p‐Smad2 and p‐Smad3, seven indices of endMT biomarkers, were significantly increased in MCT group than in the SC group, and were significantly reversed in MCT‐PTU group, suggesting PTU therapy may be potential for the PAH patients. The gene discussed is SMAD3; the disease is pulmonary arterial hypertension.