However, implantation of 4T1.2-HER2 cells in wildtype BALB/c mice led to frequent tumour rejection (27% rejection at 1 x 107 cells, 70% rejection at 1 x 106 cells), but not in athymic nude mice (Figures 1D–F), confirming substantial immunogenicity of the full length huHER2. This evidence concerns the gene ERBB2 and neoplasm.