MIF and neoplasm: As for humoral factors, VEGF [34], macrophage migration inhibitory factor (MIF) [35], IL-6 [29], IL-4/13 [36,37], IL-10, TGFβ [38], POSTN [39], colony-stimulating factor-1 (CSF-1) [40], CCL2 [41], CXCL12 [42], and COX-2/PGE2 [43] directly or indirectly regulate the immunosuppressive tumor microenvironment.