ERBB2 and breast cancer: Due to the high incidence of EGFR/Her2 signaling amplification associated with a poor prognosis in some types of human cancers such as breast cancer, lapatinib in combination with capecitabine has been approved by the Food and Drug Administration as a therapy for patients with Her2-overexpressing or metastatic breast cancer that failed to respond to anthracycline, taxane, or the previous targeting agent, anti-ErbB2 monoclonal antibody transtuzumab (Herceptin) [5-6].