Mouse Netrin-1 is a member of the laminin-related family of axon-guidance molecules, collectively referred to as Netrins (netr is Sanskrit for “one who guides”). The molecule’s cDNA encodes a 603 amino acid (aa) protein precursor that has structural similarity to the N-terminal gamma ‑chain of laminin. It contains a globular domain, three EGF repeats, and a C-terminal heparin-binding domain. Mouse Netrin-1 shares 52% aa identity with mouse Netrin-3, and 98% and 87% aa identity with human and chicken Netrin-1, respectively. Cells reported to express Netrin-1 in the embryo include cells of the floor plate, ventricular zone of the spinal cord, the brain, the ganglionic eminence, and parts of the diencephalon. Netrins were first identified for promoting the outgrowth of commissural axons and are also involved in helping migrating cells and axonal growth cones navigate to their targets. Netrins can provide both attractive and repulsive cues to neurons, depending on the receptors present and cellular context. In the adult, Netrin-1 is likely involved in axon regeneration in peripheral nerves. Netrin-1 has also been shown to be expressed outside of the nervous system and to be involved in development of such tissues as the pancreas, lung, bowel, bone and mammary gland. In non-neural organogenesis, Netrin‑1 provides an adhesive rather than guidance function. The DCC (deleted in colorectal carcinoma), Neogenin, the UNC5 family of receptors, and the adenosine A2b receptors are proposed to be functional receptors for Netrin-1 (1‑7).