It has been also reported that exosomes can stimulate cytotoxic effects on NK cells by membrane IL-15Rα and NKG2D expression, which induce proliferation and membrane IFN production [37,38] Exosomes derived from DCs, which express major histocompatibility complex (MHC) and costimulatory molecules, have been used for antitumor vaccines because, besides to be a source of tumor peptides, they also express molecules essential for the induction of immune responses, such as MHC I, MHC II and costimulatory CD40, CD54, and CD80 [39]. This evidence concerns the gene KLRK1 and neoplasm.