FAP and cancer: Cancer-associated fibroblasts are the primary stromal cells within the TME [2] and can be identified based on the expression of various ‘CAF markers’ such as fibroblast-activation-protein (FAP), platelet-derived growth factor receptor ß (PDGFRß), and alpha smooth muscle actin (αSMA), which separates them from the large pool of quiescent fibroblasts present in the body [3].