The HER2 gene amplification and/or protein overexpression is found in 15–30% of all invasive breast cancers and has been associated with more aggressive disease and shorter disease-free survival, through activation of several intracellular pathways ultimately affecting cell proliferation, survival, motility and adhesion (Baselga et al, 2005). The gene discussed is ERBB2; the disease is invasive breast carcinoma.