These include: amphiregulin (AREG), an autocrine growth factor ligand of EGFR; glypican-1 precursor (GPC1), a modulator of the mitogenic activities of ErbB receptor ligands such as HRGβ1 and AREG, and frequently upregulated in breast cancer (Matsuda et al, 2001); parathyroid hormone-related protein precursor (PTHLH), a signaller of bone remodelling found overexpressed in bone-metastasised breast cancers (Iddon et al, 1999); endothelin-2 (EDN2), stanniocalcin 1 (STC1); adrenomedullin precursor (ADM) and secretory granule proteoglycan core protein (PRG1). Here, EGFR is linked to breast cancer.