Gene Symbol: robo1
Description: roundabout 1
Alias: BEST:GM07780, CG13521, CT32892, D-Robo1, Dmel\CG13521, ROBO, Robo, Robo-1, Robo1, dRobo, dRobo1, robo, robo1S, roundabout 1, CG13521-PA, CG13521-PC, robo, robo1-PA, robo1-PC, roundabout
Species: fruit fly
Products:     robo1

Top Publications

  1. Johnson K, Ghose A, Epstein E, Lincecum J, O Connor M, Van Vactor D. Axonal heparan sulfate proteoglycans regulate the distribution and efficiency of the repellent slit during midline axon guidance. Curr Biol. 2004;14:499-504 pubmed
  2. Georgiou M, Tear G. The N-terminal and transmembrane domains of Commissureless are necessary for its function and trafficking within neurons. Mech Dev. 2003;120:1009-19 pubmed
    ..Comm is able to reduce cell surface levels of Roundabout (Robo), a receptor for the midline repellent Slit, on commissural axons and unknown inhibitors of synaptogenesis ..
  3. Gao F, Brenman J, Jan L, Jan Y. Genes regulating dendritic outgrowth, branching, and routing in Drosophila. Genes Dev. 1999;13:2549-61 pubmed
    ..These findings begin to reveal the molecular mechanisms controlling dendritic morphogenesis. ..
  4. Pappu K, Morey M, Nern A, Spitzweck B, Dickson B, Zipursky S. Robo-3--mediated repulsive interactions guide R8 axons during Drosophila visual system development. Proc Natl Acad Sci U S A. 2011;108:7571-6 pubmed publisher
    ..We found that Roundabout-3 (Robo3), an axon-guidance receptor, is expressed specifically and transiently in R8 growth cones...
  5. Spitzweck B, Brankatschk M, Dickson B. Distinct protein domains and expression patterns confer divergent axon guidance functions for Drosophila Robo receptors. Cell. 2010;140:409-20 pubmed publisher the Drosophila CNS is constructed in part under the control of three Robo family axon guidance receptors: Robo1, Robo2 and Robo3. Each of these receptors is responsible for a distinct set of guidance decisions...
  6. Liu Q, Hiramoto M, Ueda H, Gojobori T, Hiromi Y, Hirose S. Midline governs axon pathfinding by coordinating expression of two major guidance systems. Genes Dev. 2009;23:1165-70 pubmed publisher
    ..T-box protein Midline controls expression of genes encoding components of two major guidance systems: Frazzled, ROBO, and Slit...
  7. Weyers J, Milutinovich A, Takeda Y, Jemc J, Van Doren M. A genetic screen for mutations affecting gonad formation in Drosophila reveals a role for the slit/robo pathway. Dev Biol. 2011;353:217-28 pubmed publisher
    ..In addition, we discover that the Slit/Roundabout pathway, best known for its role in regulating axonal guidance, is essential for proper gonad formation...
  8. Grueber W, Yang C, Ye B, Jan Y. The development of neuronal morphology in insects. Curr Biol. 2005;15:R730-8 pubmed
    ..We speculate about how and why the actions of these genes might facilitate the diversification of dendritic morphology. ..
  9. Yang L, Garbe D, Bashaw G. A frazzled/DCC-dependent transcriptional switch regulates midline axon guidance. Science. 2009;324:944-7 pubmed publisher
    ..Slit-roundabout repulsion and netrin-deleted in colorectal cancer (DCC) (frazzled) attraction must be tightly regulated to ..

More Information


  1. Garbe D, O Donnell M, Bashaw G. Cytoplasmic domain requirements for Frazzled-mediated attractive axon turning at the Drosophila midline. Development. 2007;134:4325-34 pubmed
  2. Bodily K, Morrison C, Renden R, Broadie K. A novel member of the Ig superfamily, turtle, is a CNS-specific protein required for coordinated motor control. J Neurosci. 2001;21:3113-25 pubmed a human brain protein (KIAA1355), the Deleted in Colorectal Cancer/Neogenin/Frazzled receptor family, and the Roundabout/Dutt1 receptor family...
  3. Keleman K, Rajagopalan S, Cleppien D, Teis D, Paiha K, Huber L, et al. Comm sorts robo to control axon guidance at the Drosophila midline. Cell. 2002;110:415-27 pubmed
    Axon growth across the Drosophila midline requires Comm to downregulate Robo, the receptor for the midline repellent Slit...
  4. Al Anzi B, Wyman R. The Drosophila immunoglobulin gene turtle encodes guidance molecules involved in axon pathfinding. Neural Dev. 2009;4:31 pubmed publisher
    ..The latter two capabilities are required by migrating axons to explore densely packed targets. ..
  5. Rajagopalan S, Vivancos V, Nicolas E, Dickson B. Selecting a longitudinal pathway: Robo receptors specify the lateral position of axons in the Drosophila CNS. Cell. 2000;103:1033-45 pubmed
    ..Local cues further refine the lateral position. Together, these long- and short-range guidance cues allow growth cones to select with precision a specific longitudinal pathway. ..
  6. Mauss A, Tripodi M, Evers J, Landgraf M. Midline signalling systems direct the formation of a neural map by dendritic targeting in the Drosophila motor system. PLoS Biol. 2009;7:e1000200 pubmed publisher
    ..We show that the midline signalling systems Slit/Robo and Netrin/Frazzled are the main molecular mechanisms that underlie dendritic targeting with respect to the midline...
  7. Evans T, Bashaw G. Functional diversity of Robo receptor immunoglobulin domains promotes distinct axon guidance decisions. Curr Biol. 2010;20:567-72 pubmed publisher
    ..In Drosophila, three Roundabout (Robo) Ig superfamily receptors respond to their common Slit ligand to regulate axon guidance at the midline: ..
  8. Hummel T, Schimmelpfeng K, Klämbt C. Commissure formation in the embryonic CNS of Drosophila. Development. 1999;126:771-9 pubmed
    ..We show that the glial cells present repulsive signals to the previously described ROUNDABOUT receptor in addition to a permissive contact-dependent signal helping commissural growth cones across the ..
  9. Merianda T, Botta V, Bhat K. Patched regulation of axon guidance is by specifying neural identity in the Drosophila nerve cord. Dev Genes Evol. 2005;215:285-96 pubmed
    ..Interestingly, the medial tracts cross the midline ignoring the axon-repellant Slit on the midline and Roundabout on growth cones. The medial tract is pioneered by neurons pCC and vMP2...
  10. Keleman K, Dickson B. Short- and long-range repulsion by the Drosophila Unc5 netrin receptor. Neuron. 2001;32:605-17 pubmed
    ..Ectopic expression of Unc5 on CNS axons can elicit either short- or long-range repulsion from the midline. Both short- and long-range repulsion require Netrin function, but only long-range repulsion requires Frazzled. ..
  11. Englund C, Steneberg P, Falileeva L, Xylourgidis N, Samakovlis C. Attractive and repulsive functions of Slit are mediated by different receptors in the Drosophila trachea. Development. 2002;129:4941-51 pubmed
    ..b>Robo and Robo2 are expressed in different branches, and are both necessary for the correct orientation of branch ..
  12. Zlatic M, Li F, Strigini M, Grueber W, Bate M. Positional cues in the Drosophila nerve cord: semaphorins pattern the dorso-ventral axis. PLoS Biol. 2009;7:e1000135 pubmed publisher
    ..The mediolateral positions of sensory arbors are controlled by the response of Robo receptors to a Slit gradient...
  13. Hsouna A, Kim Y, VanBerkum M. Abelson tyrosine kinase is required to transduce midline repulsive cues. J Neurobiol. 2003;57:15-30 pubmed
    ..abnormal crossovers is enhanced by mutations in the genes encoding the midline repellent, Slit, or its receptor, Roundabout. In comm mutants, where repulsive signals remain elevated, increasing or decreasing Abl activity partially ..
  14. Grueber W, Jan Y. Dendritic development: lessons from Drosophila and related branches. Curr Opin Neurobiol. 2004;14:74-82 pubmed
    ..Here, we review some recent advances in our understanding of dendritic development in insects, focusing primarily on insights that have been gained from studies of Drosophila. ..
  15. Dimitrova S, Reissaus A, Tavosanis G. Slit and Robo regulate dendrite branching and elongation of space-filling neurons in Drosophila. Dev Biol. 2008;324:18-30 pubmed publisher
    ..In this study we show that a member of the conserved Robo receptor family, Robo, and its ligand Slit regulate the dendritic differentiation of space-filling neurons...
  16. Knox J, Moyer K, Yacoub N, Soldaat C, Komosa M, Vassilieva K, et al. Syndecan contributes to heart cell specification and lumen formation during Drosophila cardiogenesis. Dev Biol. 2011;356:279-90 pubmed publisher
    ..of diverse ligands in mammals, yet in Drosophila, genetic evidence links Syndecan only to the Slit receptor Roundabout and to the receptor tyrosine phosphatase LAR...
  17. Tayler T, Robichaux M, Garrity P. Compartmentalization of visual centers in the Drosophila brain requires Slit and Robo proteins. Development. 2004;131:5935-45 pubmed
    ..markers to characterize a boundary within the optic lobe of the Drosophila brain and found that Slit and the Robo family of receptors, well-known regulators of axon guidance and neuronal migration, inhibit the mixing of adjacent ..
  18. SANTIAGO MARTINEZ E, Soplop N, Kramer S. Lateral positioning at the dorsal midline: Slit and Roundabout receptors guide Drosophila heart cell migration. Proc Natl Acad Sci U S A. 2006;103:12441-6 pubmed
    ..In this study, we analyzed the role of Slit, an extracellular matrix protein and its transmembrane receptors Roundabout (Robo) and Roundabout2 (Robo2) during morphogenesis of the Drosophila heart tube, a process analogous to early ..
  19. Dickson B, Gilestro G. Regulation of commissural axon pathfinding by slit and its Robo receptors. Annu Rev Cell Dev Biol. 2006;22:651-75 pubmed examples, we examine how commissural axon pathfinding is regulated by the Slit family of guidance cues and their Robo family receptors...
  20. Grueber W, Ye B, Yang C, Younger S, Borden K, Jan L, et al. Projections of Drosophila multidendritic neurons in the central nervous system: links with peripheral dendrite morphology. Development. 2007;134:55-64 pubmed
    ..We have examined the effect of Robo family members on class-specific axon lamination, and have also taken a forward genetic approach to identify new ..
  21. SANTIAGO MARTINEZ E, Soplop N, Patel R, Kramer S. Repulsion by Slit and Roundabout prevents Shotgun/E-cadherin-mediated cell adhesion during Drosophila heart tube lumen formation. J Cell Biol. 2008;182:241-8 pubmed publisher
    ..We show that Slit and its receptor Roundabout (Robo) are required at CB apical domains for lumen formation...
  22. Harpaz N, Ordan E, Ocorr K, Bodmer R, Volk T. Multiplexin promotes heart but not aorta morphogenesis by polarized enhancement of slit/robo activity at the heart lumen. PLoS Genet. 2013;9:e1003597 pubmed publisher
    ..Importantly, Mp forms a protein complex with Slit, and interacts genetically with both slit and robo in the formation of the heart tube...
  23. Bashaw G, Goodman C. Chimeric axon guidance receptors: the cytoplasmic domains of slit and netrin receptors specify attraction versus repulsion. Cell. 1999;97:917-26 pubmed
    Frazzled (Fra) is the DCC-like Netrin receptor in Drosophila that mediates attraction; Roundabout (Robo) is a Slit receptor that mediates repulsion...
  24. Stevens A, Jacobs J. Integrins regulate responsiveness to slit repellent signals. J Neurosci. 2002;22:4448-55 pubmed
    ..We propose that the strength of adhesive signaling from integrins influences the threshold of response by growth cones to repellent axon guidance cues. ..
  25. Rajagopalan S, Nicolas E, Vivancos V, Berger J, Dickson B. Crossing the midline: roles and regulation of Robo receptors. Neuron. 2000;28:767-77 pubmed
    In the Drosophila CNS, the midline repellent Slit acts at short range through its receptor Robo to control midline crossing...
  26. Seeger M, Tear G, Ferres Marco D, Goodman C. Mutations affecting growth cone guidance in Drosophila: genes necessary for guidance toward or away from the midline. Neuron. 1993;10:409-26 pubmed
    ..Here we focus on two new genes: commissureless (comm) and roundabout (robo)...
  27. Fan X, Labrador J, Hing H, Bashaw G. Slit stimulation recruits Dock and Pak to the roundabout receptor and increases Rac activity to regulate axon repulsion at the CNS midline. Neuron. 2003;40:113-27 pubmed
    Drosophila Roundabout (Robo) is the founding member of a conserved family of repulsive axon guidance receptors that respond to secreted Slit proteins...
  28. Wills Z, Emerson M, Rusch J, Bikoff J, Baum B, Perrimon N, et al. A Drosophila homolog of cyclase-associated proteins collaborates with the Abl tyrosine kinase to control midline axon pathfinding. Neuron. 2002;36:611-22 pubmed
    ..for this model is provided by genetic interactions that both capt and Abl display with multiple members of the Roundabout receptor family...
  29. Rhee J, Mahfooz N, Arregui C, Lilien J, Balsamo J, VanBerkum M. Activation of the repulsive receptor Roundabout inhibits N-cadherin-mediated cell adhesion. Nat Cell Biol. 2002;4:798-805 pubmed that these two types of information are functionally integrated; activation of the transmembrane receptor Roundabout (Robo) by its ligand, the secreted repulsive guidance cue Slit, inactivates N-cadherin-mediated adhesion...
  30. Kidd T, Brose K, Mitchell K, Fetter R, Tessier Lavigne M, Goodman C, et al. Roundabout controls axon crossing of the CNS midline and defines a novel subfamily of evolutionarily conserved guidance receptors. Cell. 1998;92:205-15 pubmed
    The robo gene in Drosophila was identified in a large-scale mutant screen for genes that control the decision by axons to cross the CNS midline. In robo mutants, too many axons cross and recross the midline...
  31. Albrecht S, Altenhein B, Paululat A. The transmembrane receptor Uncoordinated5 (Unc5) is essential for heart lumen formation in Drosophila melanogaster. Dev Biol. 2011;350:89-100 pubmed publisher
    ..Our findings support the idea that Unc5 is crucial for lumen formation and thereby represents a repulsive cue acting during Drosophila heart tube formation. ..
  32. Brose K, Bland K, Wang K, Arnott D, Henzel W, Goodman C, et al. Slit proteins bind Robo receptors and have an evolutionarily conserved role in repulsive axon guidance. Cell. 1999;96:795-806 pubmed
    ..a companion to this paper, identifies the Slit protein as a candidate ligand for the repulsive guidance receptor Roundabout (Robo)...
  33. Hiramoto M, Hiromi Y. ROBO directs axon crossing of segmental boundaries by suppressing responsiveness to relocalized Netrin. Nat Neurosci. 2006;9:58-66 pubmed
    ..boundary, the longitudinal axons' responsiveness to Netrin presented on the commissure is suppressed by Roundabout (ROBO), through counteracting Gq signaling...
  34. Fritz J, VanBerkum M. Calmodulin and son of sevenless dependent signaling pathways regulate midline crossing of axons in the Drosophila CNS. Development. 2000;127:1991-2000 pubmed either signaling pathway leads to abnormal projection of axons across the midline and these increase with roundabout or slit mutations...
  35. Keleman K, Ribeiro C, Dickson B. Comm function in commissural axon guidance: cell-autonomous sorting of Robo in vivo. Nat Neurosci. 2005;8:156-63 pubmed
    ..Comm) controls axon guidance across the Drosophila melanogaster midline by regulating surface levels of Robo, the receptor for the midline repellent Slit...
  36. Medioni C, Astier M, Zmojdzian M, Jagla K, Semeriva M. Genetic control of cell morphogenesis during Drosophila melanogaster cardiac tube formation. J Cell Biol. 2008;182:249-61 pubmed publisher
    ..Furthermore, we identify a genetic pathway in which roundabout, slit, held out wings, and dystroglycan control cardiac lumen formation by establishing nonadherent luminal ..
  37. Georgiou M, Tear G. Commissureless is required both in commissural neurones and midline cells for axon guidance across the midline. Development. 2002;129:2947-56 pubmed
    ..Comm downregulates levels of Roundabout (Robo), a receptor for the midline repellent Slit, in order to allow axons to cross the midline...
  38. Zlatic M, Landgraf M, Bate M. Genetic specification of axonal arbors: atonal regulates robo3 to position terminal branches in the Drosophila nervous system. Neuron. 2003;37:41-51 pubmed
  39. Marrone A, Kucherenko M, Rishko V, Shcherbata H. New dystrophin/dystroglycan interactors control neuron behavior in Drosophila eye. BMC Neurosci. 2011;12:93 pubmed publisher
    ..Since the function of the DGC in the brain and nervous system has not been fully defined, we have here continued to analyze the DGC modifiers' function in the developing Drosophila brain and eye...
  40. Vanderploeg J, Vazquez Paz L, MacMullin A, Jacobs J. Integrins are required for cardioblast polarisation in Drosophila. BMC Dev Biol. 2012;12:8 pubmed publisher
    ..Apical accumulation of Integrins is enhanced by Robo, and reciprocally, apicalisation of luminal factors like Slit and Robo requires Integrin function...
  41. Simpson J, Bland K, Fetter R, Goodman C. Short-range and long-range guidance by Slit and its Robo receptors: a combinatorial code of Robo receptors controls lateral position. Cell. 2000;103:1019-32 pubmed
    ..Here we show that a combinatorial code of Robo receptors controls lateral position in the CNS by responding to this presumptive Slit gradient...
  42. Furrer M, Kim S, Wolf B, Chiba A. Robo and Frazzled/DCC mediate dendritic guidance at the CNS midline. Nat Neurosci. 2003;6:223-30 pubmed
    ..Using single-cell labeling, we describe specific guidance defects in dendrites of identified neurons in frazzled, robo, netrin and commissureless mutant embryos of Drosophila melanogaster...
  43. Bhat K, Gaziova I, Krishnan S. Regulation of axon guidance by slit and netrin signaling in the Drosophila ventral nerve cord. Genetics. 2007;176:2235-46 pubmed
    ..It has been hypothesized that a gradient of Slit from the midline interacts with three different Robo receptors to specify the axon tract positioning. However, no such gradient has been detected...
  44. Garbe D, Bashaw G. Independent functions of Slit-Robo repulsion and Netrin-Frazzled attraction regulate axon crossing at the midline in Drosophila. J Neurosci. 2007;27:3584-92 pubmed
    ..receptors to attract commissural axons toward and across the midline, whereas Slit signals through Robo family receptors to prevent commissural axons from recrossing the midline, as well as to prevent ipsilateral axons ..
  45. Bashaw G, Hu H, Nobes C, Goodman C. A novel Dbl family RhoGEF promotes Rho-dependent axon attraction to the central nervous system midline in Drosophila and overcomes Robo repulsion. J Cell Biol. 2001;155:1117-22 pubmed which far too many axons cross the midline, a phenotype reminiscent of loss of function mutations in the Roundabout (Robo) repulsive guidance receptor...
  46. Schimmelpfeng K, Gogel S, Klämbt C. The function of leak and kuzbanian during growth cone and cell migration. Mech Dev. 2001;106:25-36 pubmed
    ..In Drosophila, the Slit protein is a repulsive signal secreted by the midline glial cells. It binds to the Roundabout receptors, which are expressed on CNS axons in the longitudinal tracts but not in the commissural tracts...
  47. Fritz J, VanBerkum M. Regulation of rho family GTPases is required to prevent axons from crossing the midline. Dev Biol. 2002;252:46-58 pubmed
    ..Heterozygous loss of Roundabout enhances the ctDrac phenotype and causes errors in embryos expressing dnRho or ctRho...
  48. Yang L, Bashaw G. Son of sevenless directly links the Robo receptor to rac activation to control axon repulsion at the midline. Neuron. 2006;52:595-607 pubmed
    ..biology, we demonstrate that Sos is recruited to the plasma membrane, where it forms a ternary complex with the Roundabout receptor and the SH3-SH2 adaptor protein Dreadlocks (Dock) to regulate Rac-dependent cytoskeletal rearrangement ..
  49. Bashaw G, Kidd T, Murray D, Pawson T, Goodman C. Repulsive axon guidance: Abelson and Enabled play opposing roles downstream of the roundabout receptor. Cell. 2000;101:703-15 pubmed
    Drosophila Roundabout (Robo) is the founding member of a conserved family of repulsive axon guidance receptors that respond to secreted Slit proteins...
  50. Simpson J, Kidd T, Bland K, Goodman C. Short-range and long-range guidance by slit and its Robo receptors. Robo and Robo2 play distinct roles in midline guidance. Neuron. 2000;28:753-66 pubmed
    Previous studies showed that Roundabout (Robo) in Drosophila is a repulsive axon guidance receptor that binds to Slit, a repellent secreted by midline glia...
  51. Gilestro G. Redundant mechanisms for regulation of midline crossing in Drosophila. PLoS ONE. 2008;3:e3798 pubmed publisher
    ..In vertebrates and invertebrates regulation of crossing is achieved by interfering with Robo signalling either through sorting and degradation of the receptor, in flies, or through silencing of its repulsive ..
  52. Kramer S, Kidd T, Simpson J, Goodman C. Switching repulsion to attraction: changing responses to slit during transition in mesoderm migration. Science. 2001;292:737-40 pubmed
    Slit is secreted by cells at the midline of the central nervous system, where it binds to Roundabout (Robo) receptors and functions as a potent repellent...
  53. Myat A, Henry P, McCabe V, Flintoft L, Rotin D, Tear G. Drosophila Nedd4, a ubiquitin ligase, is recruited by Commissureless to control cell surface levels of the roundabout receptor. Neuron. 2002;35:447-59 pubmed
    ..In Drosophila, Roundabout reaches high levels on axons once they have crossed the midline, and this prohibits recrossing...
  54. Lundström A, Gallio M, Englund C, Steneberg P, Hemphälä J, Aspenstrom P, et al. Vilse, a conserved Rac/Cdc42 GAP mediating Robo repulsion in tracheal cells and axons. Genes Dev. 2004;18:2161-71 pubmed
    Slit proteins steer the migration of many cell types through their binding to Robo receptors, but how Robo controls cell motility is not clear...
  55. Kim Y, Fritz J, Seneviratne A, VanBerkum M. Constitutively active myosin light chain kinase alters axon guidance decisions in Drosophila embryos. Dev Biol. 2002;249:367-81 pubmed
    ..Mutations in the midline repulsive ligand Slit, or its receptor Roundabout, enhance the number of ctMLCK-induced crossovers, but ctMLCK expression also partially rescues commissure ..
  56. Brenman J, Gao F, Jan L, Jan Y. Sequoia, a tramtrack-related zinc finger protein, functions as a pan-neural regulator for dendrite and axon morphogenesis in Drosophila. Dev Cell. 2001;1:667-77 pubmed
  57. Godenschwege T, Simpson J, Shan X, Bashaw G, Goodman C, Murphey R. Ectopic expression in the giant fiber system of Drosophila reveals distinct roles for roundabout (Robo), Robo2, and Robo3 in dendritic guidance and synaptic connectivity. J Neurosci. 2002;22:3117-29 pubmed
    The Roundabout (Robo) receptors have been intensively studied for their role in regulating axon guidance in the embryonic nervous system, whereas a role in dendritic guidance has not been explored...
  58. Bossing T, Brand A. Dephrin, a transmembrane ephrin with a unique structure, prevents interneuronal axons from exiting the Drosophila embryonic CNS. Development. 2002;129:4205-18 pubmed
    ..We propose that the longitudinal tracts in the Drosophila CNS are moulded by a repulsive outer border of Dephrin expression. ..
  59. Kucherenko M, Marrone A, Rishko V, Magliarelli H, Shcherbata H. Stress and muscular dystrophy: a genetic screen for dystroglycan and dystrophin interactors in Drosophila identifies cellular stress response components. Dev Biol. 2011;352:228-42 pubmed publisher
  60. Winberg M, Noordermeer J, Tamagnone L, Comoglio P, Spriggs M, Tessier Lavigne M, et al. Plexin A is a neuronal semaphorin receptor that controls axon guidance. Cell. 1998;95:903-16 pubmed
    ..Plexins, which themselves contain complete Semaphorin domains, may be both the ancestors of classical Semaphorins and binding partners for Semaphorins. ..
  61. Kidd T, Russell C, Goodman C, Tear G. Dosage-sensitive and complementary functions of roundabout and commissureless control axon crossing of the CNS midline. Neuron. 1998;20:25-33 pubmed
    commissureless and roundabout lead to complementary mutant phenotypes in which either too few or too many axons cross the midline...
  62. Steigemann P, Molitor A, Fellert S, Jackle H, Vorbrüggen G. Heparan sulfate proteoglycan syndecan promotes axonal and myotube guidance by slit/robo signaling. Curr Biol. 2004;14:225-30 pubmed
    Slit, the ligand for the Roundabout (Robo) receptors, is secreted from midline cells of the Drosophila central nervous system (CNS)...