EREG, also known as epiregulin, is a member of the epidermal growth factor family. It can function as a ligand of EGFR (epidermal growth factor receptor), as well as a ligand of most members of the ERBB (v-erb-b2 oncogene homolog) family of tyrosine-kinase receptors. It may be a mediator of localized cell proliferation. As a mitogen it may stimulate cell proliferation and/or angiogenesis. Recombinant human EREG protein, fused to His-tag at N-terminus, was expressed in E.coli.