S100A4 and colorectal carcinoma: Nevertheless, there are commonly recognized CAF markers proteins, still under debate, like alpha-smooth-muscle actin (aSMA), fibroblast-activated protein (FAP), fibroblast-specific protein-1 (FSP1/ S100A4) and Platelet-derived growth factor (PDGF) receptors reviewed in [101,102] which have shown prognostic relevance in different tumor types including CRC [37,38,39].