Appellants Marek Kubin and Raymond Goodwin filed U.S. Patent Application Serial No. 09/667,859 (the "Application"), which claimed the DNA sequence encoding the protein known as Natural Killer Cell Activation Inducing Ligand ("NAIL"). Natural Killer ("NK") cells are a class of cytotoxic lymphocytes that have a major role in fighting tumors and viruses. NAIL is a specific type of receptor protein on the surface of the NK cells that, when stimulated, activates cytotoxic mechanisms.