Murine cell lines (4TO7, 4T1, 66cl4, ErbB2-transformed mammary tumor cells isolated from MMTV-Neu (YD) mice), and mice model (syngeneic BALB/c mice, immunodeficient NOD/SCID/IL2Rγ–/– (NSG) mice). The gene discussed is IL2RG; the disease is breast cancer.