Ligand of the EGF receptor/EGFR. Autocrine growth factor as well as a mitogen for a broad range of target cells including astrocytes, Schwann cells and fibroblasts. The immature precursor interacts with CNIH. By phorbol 12-myristate 13-acetate (PMA). AR is a protein containing cysteines in disulfide linkage(s) that are essential for its biological activity. AR may contain oligosaccharides and/or lipid moieties that are not obligatory for the biological activity. Belongs to the amphiregulin family.