EGFR/p110, soluble

The epidermal growth factor receptor (EGFR) subfamily of receptor tyrosine kinases comprises four members: EGFR (also known as HER1, ErbB1 or ErbB), ErbB2 (Neu, HER-2), ErbB3 (HER-3), and ErbB4 (HER-4) . All family members are type I transmembrane glycoprotein that has an extracellular domain which contains two cysteine-rich domains separated by a spacer region that is involved in ligand-binding, and a cytoplasmic domain which has a membrane-proximal tyrosine kinase domain and a C-terminal tail with multiple tyrosine autophosphorylation sites. Previously the cloning and expression of a 3 kb alternative EGFR transcript which encodes a 110 kDa form of the receptor (sEGFR/p110) was reported. This receptor isoform is identical to the extracellular region of the full-length 170 kDa EGFR through amino acid 603; in addition, p110 sEGFR contains 78 unique carboxy-terminal amino acids. The sEGFR/p110 is associated with the cell membrane and can be released, allowing detection in human serum and plasma. The existence of this circulating sEGFR isoform stimulated investigation of its role as a potential circulating biomarker. Several studies suggest that alterations in sEGFR levels may be useful in cancer diagnosis and in monitoring disease recurrence and outcome, especially in patients with ovarian or breast cancer. The new polyclonal antibody may be useful in determining the expression, localization, and function of sEGFR/p110, and importantly will allow to distinguish between the expression of this receptor isoform and full length EGF receptor.