Heparin-binding EGF-like growth factor (HBEGF), a member of the EGF family of growth factors, exerts its biological activity through activation of the EGFR and other ErbB receptors. Soluble mature HBEGF is proteolytically processed from a larger membrane-anchored precursor and is a potent mitogen and chemotactic factor for fibroblasts, smooth muscle cells but not endothelial cells. HBEGF activates two EGF receptor subtypes, HER1 and HER4, and binds to cell surface HSPG. The transmembrane form of HBEGF is a juxtacrine growth and adhesion factor and is uniquely the receptor for diphtheria toxin. Both forms of HB-EGF participate in normal physiological processes and pathological processes including tumor progression and metastasis, organ hyperplasia, and atherosclerotic disease. HBEGF participates in diverse biological processes, including heart development and maintenance, skin wound healing, eyelid formation, blastocyst implantation, the progression of atherosclerosis, and tumor formation, through the activation of signaling molecules downstream of ErbB receptors and interactions with molecules associated with HBEGF. tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta markedly increased HB-EGF mRNA levels in HUVEC by 12- and 7-fold, respectively, and induction of the gene by TNF-alpha was both dose- and time-dependent.