HER2 overexpression in breast cancer is associated with poor prognosis, but the production of HER2-targeted antibodies such as Trastuzumab (Herceptin) and Pertuzumab, and HER2/EGFR tyrosine kinase inhibitors such as Lapatinib, has revolutionized the treatment of HER2-positive breast cancer. The gene discussed is ERBB2; the disease is breast cancer.