CD28 and neoplasm: We co-stained freshly isolated CD8+ TILs for puromycin and the following sets of markers: (i) PD-1, TIM3, CTLA-4, and TIGIT that characterize CD8 T cell exhaustion within the tumor microenvironment (Anderson et al., 2016); (ii) the T cell receptor costimulatory proteins CD28, ICOS, SLAMF6, and CD27, pro-inflammatory IFN-γ and TNF-α cytokines, Granzyme B; (iii) tissue-resident T cells markers CD103, CD69, and CCR5 (Golubovskaya and Wu, 2016); (iv) ectonucleoside triphosphate diphosphohydrolase-1 CD39 (Takenaka et al., 2019).