The relevant role of antibodies in tumour protection is also demonstrated by the higher antibody titer in mice without tumour than in those with tumours in ECD1.5 group (Fig. 3) and by the protection induced by sera from ECD1.5 immunized mice in unvaccinated mice challenged with HER-2/neu tumour cells (Fig. 5). The gene discussed is ERBB2; the disease is neoplasm.