KLRK1 and neoplasm: It found that TEVs carry NKG2D ligands that bind directly to natural killer (NK) cells, downregulate NKG2D expression, inhibit NK cell activation and significantly reduce the recognition and killing effect of NK cells on tumors [129].TEVs can regulate macrophage polarization, organize phagocytosis of tumor cells by macrophages and enhance tumor cell drug resistance [130,131].