Illustration of the dimer of the intracellular domain of the epidermal growth factor receptor (EGFR), which contains a tyrosine kinase (red). Inactivated by the drug Afatinib (green, blue, red, and grey). EGF plays an important role in the regulation of cell growth, proliferation and differentiation. Overexpression of the EGF receptor in a number of tissues leads to cancer. Due to this, the receptor is a target for a number of anti-cancer drugs.