CCL2 and neoplasm: Specifically, MDSCs facilitate the differentiation and expansion of Tregs through IL-10 and TGF-β [37], promote regulatory B cells (Bregs) via IL-10 [38], and contribute to the polarization of tumor-associated macrophages (TAMs) toward an M2-like, tumor-promoting phenotype through the release of S100 calcium-binding protein A8/A9 (S100A8/A9) proteins and chemokines such as C–C motif chemokine ligand 2 (CCL2).