The EGF family of growth factors

Growth factors are secreted polypeptides that regulate the growth of both normal and pathologic cells. Currently, the EGF family of growth factors consists of seven members: epidermal growth factor (EGF), transforming growth factor-α (TGF-α), heparin-binding EGF-like growth factor (HB-EGF), amphiregulin (AR), betacellulin (BTC), epiregulin (EPR), and the heregulin (HRG) sub-family. A common feature among the members of EGF family is the presence of six spaced cystines in the EGF domain. The EGF family of ligands mediates its cellular effects via specific bindings to transmembrane receptor tyrosine kinases, commonly known as HER (human epidermal growth factor receptors). Abnormalities in the expression, structure, or activity of EGF receptor (also known as HER1) and HER2 receptor (also known as c-erbB2 or c-neu gene product) contribute to the development and maintenance of the malignant phenotype in a number of human cancers. Since growth factors regulate the proliferation of cancer cells by activating receptors on the surface of the cells, one obvious approach to control cell proliferation is to interfere with the growth stimulation of tumor cells by the autocrine/paracrine growth factors.