Moreover, exhaustion NK cells highly express TIGIT rather than PD1, and whether it is to knock out the TIGIT gene or to inhibit TIGIT with anti TIGIT antibody can increase the expression of CD107a, tumor necrosis factor (TNF), and other tumor suppressor factors in NK cells, enhance the tumor-killing ability of NK cells and prolong the survival time of tumor-bearing mice (8). The gene discussed is PDCD1; the disease is neoplasm.