Our evaluation of HER2-specific CTL frequency in the peripheral blood of healthy donors and patients with HER2-overexpressing breast cancer confirmed the formation of a specific immune responses against HER2/neu during the malignant process, despite the fact that this antigen is an epidermal growth factor receptor and is normally present on healthy epithelial cells of a number of organs (17). Here, ERBB2 is linked to breast carcinoma.