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. SLIT1 and SLIT2 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. In spinal cord development, may play a role in guiding commissural axons once they reached the floor plate by modulating the response to netrin. In vitro, silences the attractive effect of NTN1 but not its growth-stimulatory effect and silencing requires the formation of a ROBO1-DCC complex. May be implicated in spinal cord midline post-crossing axon repulsion. In vitro, only commissural axons that crossed the midline responded to SLIT2. In the developing visual system, appears to function as repellent for retinal ganglion axons by providing a repulsion that directs these axons along their appropriate paths prior to, and after passage through, the optic chiasm. In vitro, collapses and repels retinal ganglion cell growth cones. Seems to play a role in branching and arborization of CNS sensory axons, and in neuronal cell migration. In vitro, Slit homolog 2 protein N-product, but not Slit homolog 2 protein C-product, repels olfactory bulb (OB) but not dorsal root ganglia (DRG) axons, induces OB growth cones collapse and induces branching of DRG axons. Seems to be involved in regulating leukocyte migration (By similarity). Homodimer. Interacts with GREM1 (By similarity). Binds ROBO1 and ROBO2 with high affinity. The C-terminal cleavage protein is more diffusible than the larger N-terminal protein that is more tightly cell associated. Expressed in developing eye, in the optic stalk, and in the ventral diencephalon. According to PubMed:10864955 is expressed during retinal development by 14.5 dpc throughout the RGC layer, and is clearly restricted to the inner nuclear layer at 17.5 dpc. In the developing optic chiasm is strongly expressed at 12.5 dpc at the ventral midline of the diencephalon in the region in which the RGC axons enter the brain and turn to grow ventrally, the region expression includes the position of the glial knot. At 14.5 dpc expression is maintained at the ventral midline of the diencephalon, in a region directly dorsal to the site of axon divergence. Outside the developing brain. According to PubMed:10433822 prominently expressed in neural and mesodermally derived tissues. From 8.5 dpc to 9.5 dpc expressed strongly in the roof plate, floor plate, and notochord. Beginning at 10.5 dpc intense expression is also observed in the motor columns. By 13.5 dpc the expression decreased in the roof plate but is still retained in the floor plate and motor columns. In the rostral CNS between 8.5 dpc and 9.5 dpc expressed intensely in the dorsal neuroepithelium overlying the hindbrain, in the dorsal midline of the midbrain and forebrain, and in the ventral midbrain region. By 10.5 dpc to 11.5 dpc, additional intense expression is observed in the rhombic lip and the rostral midline. From 13.5 dpc to 17.5 dpc, the expression decreased dorsally and continued to be detected in the ventral mesencephalon and diencephalon. Outside neuronal development expressed between 8.5 dpc and 9.5 dpc in the clefts between the first, the second, and the third branchial arches. From 10.5 dpc to 11.5 dpc, expression is detected in the nasal pit, the developing eye, the otic vesicle, and the visceral grooves. From 13.5 dpc to 17.5 dpc expressed in the developing cochlea (in a pattern consistent with expression in the organ of Corti), in the olfactory epithelium and in the inner neuronal layer of the retina and in the optic nerve. At this stage also expressed in the tongue, in the tooth primordium, and in the outer root sheath of the whisker follicle in the layer surrounding the bulb. At 11.5 dpc is intensely expressed in the rostral lateral ridge flanking the forelimb buds and in lateral ridge tissue between the fore- and the hindlimb buds. Weak expression is observed in a segmented pattern in the posterior part of the sclerotome. Expression is notably absent in the base of the limb buds and weak expression is observed in the interdigital regions of the distal limb bud beginning at 11.5 dpc. By 13.5 dpc intensely expressed in interdigital mesenchyme. The leucine-rich repeat domain is sufficient for guiding both axon projection and neuronal migration, in vitro. 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).