KLRK1 and neoplasm: Equipped with NKG2D recognition sites, NK-Exos can directly target against tumor cells and are impervious to the immunosuppressive effects of TGF-β secreted from the tumor, allowing them to deliver NKG2D directly into the tumor microenvironment, where the interaction with NKG2D ligands initiates cytotoxic responses and induces tumor cell apoptosis [12,13].