Thought to act as molecular guidance cue in cellular migration, and function appears to be mediated by interaction with roundabout homolog receptors. During neural development involved in axonal navigation at the ventral midline of the neural tube and projection of axons to different regions (By similarity). SLIT1 and SLIT2 together seem to be essential for midline guidance in the forebrain by acting as repulsive signal preventing inappropriate midline crossing by axons projecting from the olfactory bulb. Interacts with GREM1 (By similarity) and ROBO1. During retinal development, is expressed at 12.5 dpc in the dorsocentral region of the retina, and at 17.5 dpc is only very weakly expressed. In the developing optic chiasm is expressed at 12.5 dpc around the junction of the optic nerve and the brain, with strongest expression dorsal to the site at which the optic stalk joins the diencephalon, and also weakly in a subset of the CD44/SSEA neurons. In the more dorsal region of the developing optic chiasm, is expressed in some distance posterior to the axons. However, more ventrally, is expressed in a region directly adjacent to the path taken by the RGC axons. By 17.5 dpc is not longer be detected at the junction of the brain and optic nerve and is only weakly expressed by the CD44/SSEA neurons. Outside the developing brain detected at between 8.5 dpc and 9.5 dpc in the primordiun of the branchial arches, between 9.5 dpc and 10.5 dpc in the posterior dermamyotome. By 11.5 dpc the expression pattern along somite boundaries was most prominent caudally. Weak expression was also observed in the nasal pit at 11.5 dpc. From 13.5 dpc to 17.5 dpc expression was observed in the trigeminal ganglion, in the olfactory epithelium, and in the neural layer of the retina in the developing eye (with strongest expression in the inner nuclear layer). Mice show significant axon guidance errors in a variety of pathways, including corticofugal, callosal and thalamocortical tracts. Mice double-deficient in SLIT1 and SLIT2 show retinal axon guidance defects and a disorganized lateral olfactory tract (LOT). Extended N-terminus.