ERBB2 and neoplasm: This was indicated by the following findings: first, ACE peptides induced stabilisation of HLA-A2.1 molecules on T2 cells and such ACE-pulsed T2 cells were efficiently lysed by our ACE-induced CTL effectors; second, HER-2/neu+, HLA-A2.1+ primary tumour cells as well as human tumour cell lines of breast and ovarian origin were lysed in an HLA-A2.1-restricted fashion since the cytotoxicity was to a great extent abrogated in the presence of the mAb BB7.2, and third, HER-2/neu-overexpressing but HLA-A2.1− human cell lines were not lysed.