S100A4 and melanoma: Resident dermal fibroblasts are the main source of CAFs in melanoma, and have been found to highly express α-SMA, among other markers of fibroblast activation and differentiation including fibroblast activation protein (FAP), fibroblast-specific protein 1 (FSP-1), osteonectin, desmin, platelet-derived growth factor receptor (PDGFR), periostin, neuron-glial antigen-2 (NG2), and vimentin [27].