CD4 and neoplasm: In addition to directly impact tumor cell survival, glycolysis alters the tumor microenvironment (TME), especially the immune cells, including the activation of natural killer (NK) cells, CD4+ T cells (14, 15), the generation of memory CD8+ T cells (Tm) (15), macrophage polarization (16) and Treg suppression function (17), etc. The accumulation of lactic acid by enhanced glycolytic activity acidifies the TME and further contributes to immunosuppression in vivo (18).