PDCD1 and neoplasm: Therefore, the activation status of T cells and tumor cells were compared, focusing on seven factors, i.e., NK cell-activating receptors from NK cells, PD-1, CXCR3, and IFNγ from T cells, and IFNγ receptor, PD-L1, and CXCL9 from the tumor, of which the last six factors are directly involved in the activation and trafficking of T cells and their interaction with tumor cells (Table 1).