PDCD1 and neoplasm: We found that tumor-infiltrating PVRIG+ NK cells expressed higher level of inhibitory receptors, many of which are also exhaustion markers, including CD96, TIGIT, Tim-3, PD-1 and NKG2A compared with PVRIG− tumor-infiltrating NK cells (Fig. 2c–e), suggesting a more exhausted phenotype of tumor-infiltrating PVRIG+ NK cells.