In all likelihood, ErbB3 signaling will also contribute to resistance to single and dual specificity EGFR and ErbB2 inhibitors (for example, lapatinib) [16], as they come into clinical use for trastuzumab-resistant ERBB2-amplified breast cancer, and to pertuzumab, an antibody inhibitor of ErbB2/ErbB3 heterodimerization [17]. This evidence concerns the gene ERBB2 and breast cancer.