ACTA1 and pulmonary hypertension: Conversely, recent evidence demonstrated that endothelial cells can transition into mesenchymal cells expressing αSMA or smooth muscle-myosin heavy chain markers, that intimal lesions in pulmonary hypertension contained some cells co-expressing VWF and αSMA in vivo, and that this process can contribute to the accumulation of SMCs in pulmonary vascular diseases.