The family of signal transduction proteins that has received the most attention to date are the Epidermal Growth Factor Receptor (EGFR) family, most likely as several of its members are manifestly involved in stimulating tumour growth and concepts of drug action are clear (Yarden and Sliwkowski, 2001; Mosesson and Yarden, 2004; Warren and Landgraf, 2006). The gene discussed is EGFR; the disease is neoplasm.