FOXP3 and glioblastoma: In other words, high levels of lactate in the GBM TME modulates RNA splicing only in the Treg cell (Foxp3-dependent, meaning it does not affect RNA splicing in other T-cells) to increase CTLA-4 expression on the Treg cell surface, thus enhancing its immunosuppressive effects and preventing effector T-cells from infiltrating and attacking the GBM tumor cells.