Immune suppression also plays an important role in GBM progression through a variety of mechanisms, including recruitment of M2-associated macrophages to the tumor microenvironment [34] and expression of potent immunosuppressive factors including TGF-β (transforming growth factor beta) and PD-L1 (programmed death-ligand 1) [35]. The gene discussed is TGFB1; the disease is neoplasm.