ERBB2 and colonic neoplasm: In HER2-amplified colon cancer cells monotherapy with either HER2 tyrosine kinase inhibitor or anti-HER2 antibodies was almost ineffective, whereas only the combination of a monoclonal antibody, trastuzumab, and a tyrosine kinase inhibitor, lapatinib, induced a significant anti-proliferative activity (Fig. 1a-e).