S100A4 and neoplasm: Endothelial cells of tumor vessels can undergo an endothelial-mesenchymal transition (EndMT) and acquire thephenotype and functional features of CAFs with the loss ofendothelial cells molecular markers, such as the endothelialcell/platelet adhesion molecule (CD31), and the acquisition ofmarkers specific for mesenchymal cells, such as α-SMA andfibroblast specific protein 1 (FSP-1) (Zeisberg et al., 2007).