CTLA4 and neoplasm: CTLA-4 functions by outcompeting the co-stimulatory receptor CD28 for binding to ligands CD80 and CD86 on antigen-presenting cells, leading to an inhibitory signal that dampens T-cell activation (64).​ Essentially, the glycolytic lactate in GBM promotes Treg cell function and tumor evasion of the body’s immune system.