EGFR and cancer: An abnormality in the EGFR system, such as overexpression and/or mutation of EGFR, increased production of the ligands (e.g., EGF) of EGFR, or downregulation of EGFR, can interfere with the tight regulation of these signaling pathways [6] and lead to the development of epithelial malignancies in humans such as cancers [7].