ERBB2 and neoplasm: To characterize naturally arising anti-tumour immune responses upon 4T1.2-HER2T tumour implantation, serum anti-HER2T IgG (Figure 3D) was measured at D10 post-implantation, revealing minimal HER2T-reactive IgG in 4T1.2 or 4T1.2-HER2T tumour bearing mice, contrary to higher levels observed in 4T1.2-HER2 tumour bearing mice.