CHI3L1 and neoplasm: Recruitment of tumor-promoting myeloid cells by CAFs is associated with shaping their functional differentiation toward an immunosuppressive phenotype: Secretion of Chitinase-like protein 3 (Chi3L1) by mammary CAFs was shown to drive an M2-like phenotype in recruited macrophages, associated with reduced infiltration of CD8+ T lymphocytes (19).