PDCD1 and neoplasm: In another study, Clarke et al. reported a TIM3+IL7R-tissue-resident memory T cells (T rm) subset uniquely present at the tumor site and expressing high levels of PD-1 and other molecules linked to inhibitory functions; however, functionality analysis revealed that these cells were not exhausted.138 Compared with non-Trm cells, PD-1-expressing Trm cells were associated with the key effector cytokines IL-2, TNF, and IFN-γ as well as granzyme molecules.