CHI3L1 and cancer: Cancer-associated fibroblasts (CAFs) can recruit adaptive and innate immune cells to the tumor microenvironment by producing chemokines and cytokines, such as CC-chemokine ligand (CCL) 2, CCL5, CXC-chemokine ligand (CXCL) 8, CXCL12, chitinase 3-like protein 1 (CHI3L1) and IL-6 [61, 62, 67–69].