By applying this strategy, four CAF subsets, referred to as CAF-S1 to S4, were defined in human BC, based on the expression of six markers, including FAP, smooth-muscle α actin (SMA), integrin β1 (CD29), S100-A4/FSP1, PDGFRβ, and CAV1 (12, 20, 21). This evidence concerns the gene S100A4 and breast cancer.