Although molecular drugs that specifically target one or several members of the HER signalingnetwork can affect the expression and/or activation status of the HER2 oncoprotein, accumulatingevidence suggests that the actual repercussions of HER2-targeting drugs (e.g., theanti-HER2 monoclonal antibody trastuzumab or the dual HER1/HER2 tyrosine kinase inhibitor lapatinib)for tumor growth inhibition are closely related to the ability of these drugs to efficiently impedespecific signaling pathways downstream of HER2 [1-8]. This evidence concerns the gene ERBB2 and neoplasm.