With the identification of human epithelial growthfactor receptor 2 (HER2) amplification in human breast cancer [5,6], the observation that MMTV drivenexpression of the activated rat form of HER2 (NeuNT) resulted in breast cancerreinforced the importance of HER2 as a driving oncogene [7]. The gene discussed is ERBB2; the disease is neoplasm.