KLRK1 and neoplasm: For example, PC-secreted exosomes expressing NKG2D ligands on the surface induced the downregulated expression of NKG2D on the surface of natural killer (NK) and CD8+ T cells, leading to a decrease in the cytotoxic effect of these killer cells and thus enabling PC cell immune escape [97], whereas a tumor antigen-specific T-cell response produced by DCs was significantly enhanced when Rab27a was added to cells to inhibit exosome release [98].