Human sDLL-1 comprises the extracellular signaling domain of DLL1, a member of a structurally-related family of single-pass type I trans-membrane proteins that serve as ligands for Notch receptors. It is expressed in the heart and pancreas, and to a lesser extent in various other tissues. DLL-1 functions to specifically activate the Notch-1 and Notch-2 receptors. Alternative Names: sDLL-1 protein, Delta-like protein 1 protein, Delta-1 protein, sDLL1, sDLL 1 protein, sDLL 1, sDLL-1 protein, sDLL-1