S100A4 and pulmonary arterial hypertension: Indeed, a simultaneous expression of endothelial markers (CD31, von Willebrand factor, and vascular endothelial (VE)-cadherin) and myofibroblast markers (α-smooth muscle actin (α-SMA), S100A4/fibroblast specific protein-1, and type I collagen) has been observed in ECs from SSc skin and lungs, where this transdifferentiation may contribute to both SSc-related PAH and interstitial lung disease (ILD) [12,14].