CTLA4 and cancer: It has been reported that Tregs consume free fatty acids more effectively than Teffs in cancer patients due to the greater lipid uptake capacity [12, 36], which is related to the specific expression of CD36, Foxp3, PD-1, TFEB, LKB1, CTLA-4, FOXO1, and co-stimulatory molecule OX40 (Fig. 3).