TGFB1 and glioblastoma: It is believed that GME stromal cells participate in a two-way dialogue with the GBM cells, promoting an immunosuppressive GME [75], including tumor-infiltrating immune T regulatory cells (Tregs), MSCs, together with decreased expression of costimulatory molecules and the secreted immunosuppressive factors, such as TGF-β, interleukins (IL-10 IL-6), and indoleamine 2,3-dioxygenase (IDO), which inhibits immune effector activation and prevents antitumor immune responses [76,77].