Studies have found that glioma cells express many factors related to the proliferation of MDSCs (IL-6, IL-10, VEGF, PGE-2, GM-CSF, and TGF-β2); however, blocking the chemokine CCL2 signaling pathway in glioma cells effectively reduces the recruitment of MDSCs (94). This evidence concerns the gene TGFB2 and central nervous system cancer.