In this study, MCT induced pulmonary vascular endothelial cells (EC) to undergo EndMT, which showed that EC cells acquired the smooth muscle cell (SMC) marker (up-regulated in TAGLN expression) and lost the EC marker (down-regulated in PECAM1 expression), suggesting that PAH-related stress promoted the formation of pulmonary vascular neointima in SD rats. The gene discussed is TAGLN; the disease is pulmonary arterial hypertension.