Ligand for multiple Notch receptors and involved in the mediation of Notch signaling. May be involved in cell-fate decisions during hematopoiesis. Seems to be involved in early and late stages of mammalian cardiovascular development. Inhibits myoblast differentiation. Enhances fibroblast growth factor-induced angiogenesis (in vitro). Interacts with NOTCH2 and NOTCH3. Interacts with NOTCH1 (in the presence of calcium ions). Widely expressed in adult and fetal tissues. In cervix epithelium expressed in undifferentiated subcolumnar reserve cells and squamous metaplasia. Expression is up-regulated in cervical squamous cell carcinoma. Expressed in bone marrow cell line HS-27a which supports the long-term maintenance of immature progenitor cells. Note: This description may include information from UniProtKB.