KLRK1 and neoplasm: The major molecules involved in tumor immune surveillance, as recognized in knockout mouse models, consist of interferon-g (IFNg); perforin; tumor necrosis factor-related apoptosis-inducing ligand (TRAIL); IL12 and its contributing apoptosis-inducing receptors DR4 and DR5; the recombination activating genes RAG1 and RAG2, which are critical for T cell development; the T cell receptor; and the activating NK cell receptor NKG2D [42].