The levels of mRNA or protein markers of Treg infiltration into GBM tumors have been linked with poor outcome, including Forkhead Box P3 (FOXP3) [23], Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA4) [24,25], glucocorticoid-induced TNFR-related protein (GITR, (the TNFRSF18 gene product)) [20,26] and GATA-binding protein 3 (GATA3) [27]. The gene discussed is TNFRSF18; the disease is glioblastoma.