ACTA1 and breast carcinoma: Possible CAF markers including α‐SMA, fibroblast activation protein alpha, fibroblast‐specific protein‐1 (also known as S100A4), tenascin‐C, platelet‐derived growth factor receptor‐α/β, and podoplanin have been identified.6, 11 Although these CAF markers are useful for predicting the outcomes of some human breast carcinoma cohorts,12, 13 none fully or exclusively identifies activated tumor‐promoting CAFs due to various differences in fibroblast populations, as exemplified by resident fibroblasts and bone‐marrow‐derived progenitors present in tumors.