CD8A and neoplasm: In the literature, the research studies have suggested that reduced production of phosphoenolpyruvate (PEP), a glycolytic metabolite of CD8+ T cells and CD4+ T cells, was detrimental to the immune surveillance of T cells due to the competition for glucose by tumor cells, which may be related to the defective Ca 2+-NFAT signaling and T-lymphocyte activation [70].