ERBB2 and breast neoplasm: In a wide range of human carcinomas (breast, pancreas, colon, head and neck, lung, etc.), EGFR and/or HER2 are significantly overexpressed, usually following gene amplification.6 Such gene amplification has been associated with a poor prognosis in a number of cancer types for both EGFR and HER2.7 However, while a correlation exists between the HER2 overexpression status in breast tumors and their sensitivity to HER2 inhibitors, such a correlation has failed to materialize in clinical trials involving EGFR inhibitors,8 leaving a gap in our understanding of tumor dependency on EGFR signaling.