Six fibroblast markers (Costa et al., 2018) [fibroblast activation protein (FAP), integrin b1 (ITGB1), a-smooth muscle actin (aSMA), fibroblast-specific protein-1 (FSP-1), platelet-derived growth factor receptor b (PDGFRB), and caveolin-1 (CAV1)] have been used to delineate CAFs subtypes which were linked to immunosuppression and resistance to immunotherapy in breast cancer (Kieffer et al., 2020). This evidence concerns the gene FAP and breast cancer.