This is exemplified by the anti-CD20 mAb Rituximab and the anti-human epidermal growth factor receptor 2 (HER2)/neu mAbs Trastuzumab (Herceptin), the first clinically available antitumor antibodies, which have become a mainstay of therapy in patients with B cell non-Hodgkin’s lymphoma and HER2+ breast cancer, respectively [1,2]. Here, ERBB2 is linked to breast carcinoma.