Amphiregulin is an EGF related growth factor that signals through the EGF/TGF-a receptor, and stimulates growth of keratinocytes, epithelial cells and some fibroblasts. Amphiregulin also inhibits the growth of certain carcinoma cell lines. Synthesized as a transmembrane protein, Amphiregulin's extracellular domain is proteolytically processed to release the mature protein. There are 6 conserved cysteine residues, which form 3 intramolecular disulfide bonds essential for biological activity. Recombinant human Amphiregulin is a 11.3 kDa glycoprotein consisting of 98 amino acid residues.