ERBB2 and breast cancer: Third, the analysis of the humoral response induced in immunized MMTV.f.huHER2(Fo5) mice shows that both a robust anti-scFv69 (Ab3) Th1 and an anti-HER2 (Ab1') Th2 response were associated with the delay of mammary tumor onset observed in animals treated with anti-Id scFv69.