CD4 and neoplasm: IL-2 and its receptor subunits (IL-2Rα and IL-2Rβ) are critical for T cell-dependent control of tumor progression induced by CTLA-4 blockade, which could change the functional profile of the suppressive CD4+Lag3+ T cells to the regulatory Foxp3− T cells, tobecome the major source of intratumoral IL-2 [47].