Fig. 1

CAF biomarkers and functions. CAF subgroups identified by different biomarkers play distinct roles in tumor microenvironment. A Biomarkers suggesting cancer-promoting functions. Most biomarkers represent cancer-promoting CAFs including traditional CAF biomarkers (FAP, POSTN, PDGFRα/β, and FSP-1) as well as some emerging markers (CD90, Palladin, OPN, AEBP1, Twist, TNC, Gallectin1, CD10 and GPR77). They promote cancer progression though secreting cytokines and exosomes, remolding ECM, metabolic reprogramming, forming anterior niche in lung metastasis and immunosuppressive microenvironment, etc. B Biomarkers indicating cancer-restraining functions. Meflin⁺ CAFs are associated with favorable therapeutic response to ICB; CD146⁺CAF maintains sensitivity to tamoxifen of ER positive breast cancer. Both are related to better pathological histological features and prognosis of patients. C Biomarkers showing bidirectional functions. Cav-1, PDPN and CD200 labeled CAFs have both tumor-promoting and tumor-suppressing functions