PDCD1 and neoplasm: Notably the in vitro exhausted cells had a considerably higher expression of PD1, CD39, and Granzyme B compared to those from the tumors, likely due to timepoint that was assessed not enabling the full development of an exhausted phenotype in vivo and comparing to a bulk population of CD8 T cells where only a subset of CD8 will have a TCR that can detect tumor antigens.