S100A4 and breast cancer: Based on the relative co-expression of six fibroblastic markers (αSMA, FAPα (fibroblastic-activated protein α), integrin β1/CD29, S100-A4/FSP1, PDGFRβ, and CAV1 (caveolin 1), Costa et al. identified, by fluorescent analysis cell-sorting, four distinct CAF subsets in human breast cancer that accumulate differentially in tumors and juxta-tumors, one of these being functionally endowed with immunosupressive properties [213].