ERBB2 and breast carcinoma: Significant amount of research has been dedicated to elucidate molecular mechanisms that could explain de novo and acquired resistance to the anti-HER2 monoclonal antibody trastuzumab (Tzb; Herceptin®), the first immunotherapeutic drug for the successful treatment of breast carcinomas overexpressing the HER2 (erbB-2) oncogene [1]–[8].