ERBB2 and breast cancer: Several drugs capable of specifically targeting the HER2 pathway have been developed for use in both early and late HER2-positive disease and have had a significant impact on the treatment of HER2-positive breast cancer (Arteaga et al., 2012); these include antibodies directed against HER2, such as trastuzumab and pertuzumab, and small molecule tyrosine kinase inhibitors that target the kinase activity of HER2 and HER1, such as lapatinib.