In addition to TKIs, several MAbs that target either EGFR (e.g., cetuximab), ErbB2 (trastuzumab), or ErbB2 dimerization (pertuzumab), are becoming major therapeutics, in particular for the ErbB2-positive breast cancer subtype where combination of anti-ErbB2, e.g., trastuzumab with conventional chemotherapy, has drastically changed the patients' prognosis and outcome (Piccart-Gebhart et al., 2005; Romond et al., 2005). Here, ERBB2 is linked to breast cancer.