CAFs also enhance monocyte differentiation into M2-like tumor-associated macrophages via secretion of IL-6 and GM-CSF in vitro and increase IL-6 and GM-CSF, infiltrating tumor-associated macrophages and metastases in vivo, effects dependent on these cytokines in an orthotopic mixed CAF–tumor cell transplant [490]. Here, IL6 is linked to neoplasm.