TGFB1 and glioma: The immunosuppression in glioma occurs due to the increased synthesis of immunosuppressive cytokines (IL-6, IL-10, TGF-β and PGE2), as well as tumor-promoting cytokines (IL-1 and bFGF), inhibition of T-cell proliferation and effector responses, activation of Tregs, and suppression of NK-cell activity [118]–[120].