PDCD1 and cancer: To further dichotomize between tumor-reactive CD8 T cells, which can become dysfunctional or exhausted (TEX) in certain cancer types (Pritykin et al., 2021) and are usually the target of checkpoint blockade therapy, and tissue-resident CD8 T cells, we costained CD39 and PD1 in tissue from liver cancer, normal tissue adjacent to the liver tumor (NAT), and in skin, fat, and blood of patients undergoing abdominal wall or abdominoplasty surgery (Fig. 6 D).