ERBB2 and breast cancer: Amplification and overexpression of ERBB2 (also known as HER2), have been extensively documented in various human solid tumors (Komoto et al., 2009), including breast cancer (Yaziji et al., 2004), ovarian cancer (Vermeij et al., 2008), gastric cancer (Garcia et al., 2003), and salivary gland tumors (Press et al., 1994).