The Epidermal Growth Factor system is present in human organs and play important role in cell proliferation, differentiation and apoptosis during embryogenesis and postnatal development. It has four receptors (EGFR, ErbB-2, ErbB-3 and ErbB-4) and numerous ligands. ErbB receptors are trans-membrane glycoproteins. Their dimerization leads to intracellular kinase activation. As a result, a number of tyrosine residues in the COOH-terminal portion of ErbB receptors become phosphorylated. Those

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... orylated tyrosine residues function as docking sites for cytoplasmic proteins. Recruitment of proteins initiates intracellular signaling via several pathways: 1. Ras / Raf / mitogen-activated protein kinase (MAPK) pathway (regulates cell proliferation and survival). 2. Phosphatidylinositol 3-kinase (PI3K) / Akt pathway (regulates cell growth, apoptosis, tumor invasion, migration and resistance to chemotherapy). 3. Signal transducers and activators of transcription (STAT) pathway (regulates oncogenesis and tumor progression). 4. Src Kinase pathway (regulates cell proliferation, migration, adhesion, angiogenesis and immune function). 5. Phospholipase Cγ / protein kinase C pathway. Dysregulation of the Epidermal Growth Factor system signaling network, is implicated in the pathogenesis of various disorders. Especially in cancer, it becomes hyperactivated with various mechanisms (ligand overproduction, receptor overproduction, constitutive receptor activation). It is also contributes in proliferation, transformation, angiogenesis, migration and invasion. During menstrual cycle, ErbB receptors have different levels in normal endometrium. Moreover due to the inactive status of postmenopausal endometrium, it is expectable to find significantly higher expression of the 4 ErbB receptors in endometrial cancer tissue. Especially in patients with type II endometrial cancer (papillary serous or clear cell), there are high expression levels of ErbB receptors. Among them, many patients with dismal outco [...]