HB-EGF (Heparin-Binding EGF-like growth factor), also known as DTR, is produced by bronchial epithelium, visceral and vascular smooth muscle, CD4+ T cells, cardiac muscle, glomerular podocytes, keratinocytes, and IL-10-secreting regulatory macrophages. It activates both the EGF R/ErbB1 and ErbB4 receptors and has been linked to many cellular processes including proliferation, apoptosis, cell migration/invasion, differentiation, morphogenesis, and development. HB-EGF is also involved in several aspects of cancer development and progression.