Moreover, the complete absence of the natural cytotoxic receptor, NKp44, in mice [98] and lack of expression of NKG2D ligand in B16F10 melanoma cells [99] indicate that IK14004-mediated activation of NK cells via expression of NKp44/NKG2D, as shown in human cells [25], is unlikely to account for the suppression of melanoma lung tumours by peptide. This evidence concerns the gene KLRK1 and melanoma.