CCL2 and neoplasm: In addition, the tumor-associated stroma may also interact with MDSCs to encourage their expansion and enhance their function; a recent study demonstrated the capability of PSCs to secrete several cytokines and chemokines that promoted the differentiation of peripheral blood mononuclear cells into immunosuppressive MDSCs, including IL-6, VEGF and macrophage colony-stimulating factor (M-CSF), and SDF-1 and monocyte chemoattractant protein-1 (MCP-1), respectively [176].