Notch 1 is a type 1 membrane protein that serves as a receptor for the membrane bound ligands jagged-1 and -2 and delta-1 to regulate cell fate determination through the implementation of differentiation, proliferation and apoptotic programs. Upon ligand binding, the Notch intracellular domain (NICD) is released by proteolytic processing and subsequently translocates to the nucleus where it forms a transcriptionally active complex with RBP-J kappa to activate genes of the enhancer of split locus. Notch-1 may also be involved in cell specification and/or differentiation and body segment determination in the postimplantation embryo. In the adult animal, Notch-1 is highly expressed in the brain, lung, and thymus with lower expression levels in the spleen, bone-marrow, spinal cord, eyes, mammary gland, liver, intestine, skeletal muscle, kidney and heart.