Diverse cytokines and factors, including VEGF, granulocyte-macrophage colony stimulating factor (GM-CSF), IL-6, IL-10, TGF-β, interferon (IFN)-γ, IL-1β, and CCL2, are main attractors of MDSCs toward tumor tissue and affect their activation (Figure 1C) [36]. Here, CCL2 is linked to neoplasm.