CCL2 and glioma: TAMs produce many proteins that can enhance glioma proliferation and/or migration, such as stress-inducible protein 1 (STI1), epidermal growth factor (EGF), colony-stimulating factor 1 (CSF-1), chemokine ligand 2 (CCL2), interleukin-6 (IL-6), and transforming growth factors: TGF-β and -β2 [58].