S100A4 and neoplasm: Although tumor stromal fibroblasts in general may express α-SMA, FAP, vimentin, neuron-glial antigen-2 (NG2) chondroitin sulfate proteoglycan, PDGFRβ, prolyl 4-hydroxylase and FSP1; α-SMA and FAP can be used to discriminate myofibroblasts form fibroblasts in the tumor tissue (Figure 3) (73).