ERBB3 and cancer: Her2 (also known as Neu or ErbB2), a receptor tyrosine kinase belonging to the human epidermal growth factor receptor (EGFR) family that also includes EGFR/Her1, Her3, and Her4, is an important component of cell-signaling networks, and is implicated in the growth of a variety of cancers (Hynes and Lane, 2005; Riese et al., 2007; Baselga and Swain, 2009; Lemmon and Schlessinger, 2010).