As reported previously [32], most human sarcomas display a high metastatic ability in Rag2-/-;Il2rg-/- mice, which constitutively lack T, B, and NK immune response, showing a distinctive pattern of organ preference involving mainly liver, lung and other sites such as lymph nodes, interscapular brown fat pad, kidneys, and adrenal glands. The gene discussed is IL2RG; the disease is sarcoma.