Natural killer cells (NKs) have a rather unique role in the anti-tumor immunity because they are not restricted to recognizing tumor-specific antigens (this might be particularly important in the case of highly heterogeneous tumors), but can recognize the lack of the expression of MHC I complexes (for example, KIR-mediated), recognize AB-opsonized cells through FcRγIIIa (antibody-mediated cytotoxicity), and recognize stressed cells via MICA, MICB, and ULBP family proteins binding to NKG2D receptors [101,102]. The gene discussed is MICA; the disease is neoplasm.