A research group led by Professor Sachie Hiratsuka, of the Institute for Biomedical Research, Shinshu University, has found that a specific sequence of messenger RNA (mRNA), which exists outside cells, binds to receptors on the surface of natural killer (NK) cells and is taken up into the nucleus. The group found that NK cells with mRNA uptake are able to enhance their migration activity and interferon gamma production. Furthermore, NK cells incorporating the mRNA showed an inhibitory effect on cancer metastasis in animal experiments.