EGFR antibody [29.1]

The receptor for Epidermal Growth Factor is an integral cell membrane protein of 170 kDa, which spans the membranes of a wide range of normal and malignant epithelial cells. It is a tyrosine-specific protein kinase with the capacity to phosphorylate tyrosine residues located near its carboxy-terminus. EGF-R has anextracellular region which binds EGF and consequently mediates the initial response of cells to EGF and an intra- cellular region which posseses the tyrosine kinase activity. As a result of EGF binding to its specific receptor, there is increased DNA synthesis as well as other events such as cell proliferation, differentiationand repair of damaged epithelial tissue. The EGF-R has a half-life of approximately 10 hours in human fibroblasts, but in the presence of EGF this value is reduced to about 1 hour. A close similarity has been found between the sequence of the v-erb-B oncogene and the cytoplasmic and transmembrane part of the EGF-R (truncated EGF-R). It is hypothesized that an inappropriate activation of the human erb-B gene either by truncation or overexpression plays a role in the development of the malignancy. This hypothesis is supported by studies which have shown an increased number of EGF-R in various malignant tumors. High levels of EGF-R have been identified in sarcomas, gliomas, gynecological, breast, bladder and lungtumors.