Molecular Targeting in Radiotherapy: Epidermal Growth Factor Receptor

The Epidermal Growth Factor Receptor (EGFR) signaling network. The EGFR is activated upon ligand binding [either EGF or Tumor Growth Factor–α (TGFα)], which promotes homo- or heterodimerization, autophosphorylation (small spheres located on the cytoplasmic domains of receptors), and internalization. Signaling intermediaries include Ras–Raf–MAPK (for proliferation response), PI3K–AKT (for antiapoptotic response), and PKC (for cell cycle progression). PI3K, phosphoinositide 3-kinase; Jak, Janus kinase; STAT, signal transducer and transactivator; PKC, protein kinase C; PLC, phospholipase C; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor–kappa B.