It is suggested that the secretion of pro-inflammatory cytokines IL-1, IL-6, IL-8, IL-10, TGF-β, and chemokines C-X-C chemokine ligand (CXCL)-1 and CXCL-2 by CAFs could promote monocyte recruitment and the differentiation of cancer-associated macrophages from M1 to M2 [31, 57, 58]. Here, IL6 is linked to cancer.