Gene Symbol: ato
Description: atonal
Alias: ATO, Ato, CG7508, Dmel\CG7508, ato1, ato[Dm], bHLHa10, atonal, CG7508-PA, ato-PA, atona
Species: fruit fly
Products:     ato

Top Publications

  1. Hassan B, Bellen H. Doing the MATH: is the mouse a good model for fly development?. Genes Dev. 2000;14:1852-65 pubmed
  2. Powell L, zur Lage P, Prentice D, Senthinathan B, Jarman A. The proneural proteins Atonal and Scute regulate neural target genes through different E-box binding sites. Mol Cell Biol. 2004;24:9517-26 pubmed
    ..related proneural bHLH transcription factors required for the genesis of Drosophila sense organ precursors (Atonal and Scute)...
  3. Sprecher S, Pichaud F, Desplan C. Adult and larval photoreceptors use different mechanisms to specify the same Rhodopsin fates. Genes Dev. 2007;21:2182-95 pubmed
    ..Therefore, even though the larval PRs and adult R8 PRs express the same rhodopsins (rh5 and rh6), they use very distinct mechanisms for their specification. ..
  4. Quan X, Denayer T, Yan J, Jafar Nejad H, Philippi A, Lichtarge O, et al. Evolution of neural precursor selection: functional divergence of proneural proteins. Development. 2004;131:1679-89 pubmed basic helix-loop-helix (bHLH) proneural transcription factors in the peripheral nervous system (PNS) by atonal related proteins (ARPs) presents an excellent model in which to address this issue...
  5. Sun Y, Jan L, Jan Y. Transcriptional regulation of atonal during development of the Drosophila peripheral nervous system. Development. 1998;125:3731-40 pubmed
    b>atonal is a proneural gene for the development of Drosophila chordotonal organs and photoreceptor cells. We show here that atonal expression is controlled by modular enhancer elements located 5' or 3' to the atonal-coding sequences...
  6. Pepple K, Atkins M, Venken K, Wellnitz K, Harding M, Frankfort B, et al. Two-step selection of a single R8 photoreceptor: a bistable loop between senseless and rough locks in R8 fate. Development. 2008;135:4071-9 pubmed publisher
    ..mechanisms that restrict R8 potential to a single cell from within a group of cells expressing the proneural gene atonal (ato)...
  7. Escudero L, Freeman M. Mechanism of G1 arrest in the Drosophila eye imaginal disc. BMC Dev Biol. 2007;7:13 pubmed
    ..The unexpectedly complex network of regulation may reflect the importance of cells being uniformly ready to respond to the inductive signals that coordinate retinal differentiation. ..
  8. Lopes C, Casares F. hth maintains the pool of eye progenitors and its downregulation by Dpp and Hh couples retinal fate acquisition with cell cycle exit. Dev Biol. 2010;339:78-88 pubmed publisher
    ..the burst of string/cdc25 expression that precedes G1 arrest, and also the early expression of the proneural gene atonal. Thereby, hth maintains the proliferative and undifferentiated state of eye progenitors...
  9. Jarman A, Grau Y, Jan L, Jan Y. atonal is a proneural gene that directs chordotonal organ formation in the Drosophila peripheral nervous system. Cell. 1993;73:1307-21 pubmed
    ..We report the isolation of a gene, atonal (ato), with evidence that it is a proneural gene for the formation of chordotonal organs...

More Information


  1. Gupta B, Rodrigues V. Atonal is a proneural gene for a subset of olfactory sense organs in Drosophila. Genes Cells. 1997;2:225-33 pubmed
    ..We show that the basic helix-loop-helix (bHLH) transcription factor encoded by atonal (ato) is a proneural gene for one morphological type of olfactory sensilla on the antenna and for all the ..
  2. Li Y, Jiang Y, Chen Y, Karandikar U, Hoffman K, Chattopadhyay A, et al. optix functions as a link between the retinal determination network and the dpp pathway to control morphogenetic furrow progression in Drosophila. Dev Biol. 2013;381:50-61 pubmed publisher
  3. Suzuki T, Saigo K. Transcriptional regulation of atonal required for Drosophila larval eye development by concerted action of eyes absent, sine oculis and hedgehog signaling independent of fused kinase and cubitus interruptus. Development. 2000;127:1531-40 pubmed
    Bolwig's organ is the larval light-sensing system consisting of 12 photoreceptors and its development requires atonal activity...
  4. Choi C, Vilain S, Langen M, Van Kelst S, De Geest N, Yan J, et al. Conditional mutagenesis in Drosophila. Science. 2009;324:54 pubmed publisher
    ..IMAGO should also be applicable to other genetic model organisms. ..
  5. Jarman A, Ahmed I. The specificity of proneural genes in determining Drosophila sense organ identity. Mech Dev. 1998;76:117-25 pubmed
    The proneural genes (atonal and the genes of the achaete-scute complex (AS-C)) are required for the selection of sense organ precursors. They also endow these precursors with sense organ subtype information...
  6. Frankfort B, Mardon G. Senseless represses nuclear transduction of Egfr pathway activation. Development. 2004;131:563-70 pubmed
    ..An analogous relationship exists between Senseless and Egfr pathway orthologs in T-lymphocytes, suggesting that this mode of repression of Egfr signaling is conserved. ..
  7. Jhaveri D, Saharan S, Sen A, Rodrigues V. Positioning sensory terminals in the olfactory lobe of Drosophila by Robo signaling. Development. 2004;131:1903-12 pubmed
    ..The location of sensory arbors at distinct positions within the lobe allows short-range interactions with projection neurons leading to formation of the glomeruli. ..
  8. zur Lage P, Prentice D, Holohan E, Jarman A. The Drosophila proneural gene amos promotes olfactory sensillum formation and suppresses bristle formation. Development. 2003;130:4683-93 pubmed
    ..Recently amos was identified as a new candidate Drosophila proneural gene related to atonal. Having isolated the first specific amos loss-of-function mutations, we show definitively that amos is required to ..
  9. Jafar Nejad H, Acar M, Nolo R, Lacin H, Pan H, Parkhurst S, et al. Senseless acts as a binary switch during sensory organ precursor selection. Genes Dev. 2003;17:2966-78 pubmed
    ..In the presumptive SOPs that express high levels of Sens, it acts as a transcriptional activator and synergizes with proneural proteins. We therefore propose that Sens acts as a binary switch that is fundamental to SOP selection...
  10. Overstreet E, Fitch E, Fischer J. Fat facets and Liquid facets promote Delta endocytosis and Delta signaling in the signaling cells. Development. 2004;131:5355-66 pubmed
    ..We propose that Faf plays a role similar to that of Neur in the Delta signaling cells. By deubiquitinating Lqf, which enhances the efficiency of Delta internalization, Faf stimulates Delta signaling. ..
  11. Vaessin H, Brand M, Jan L, Jan Y. daughterless is essential for neuronal precursor differentiation but not for initiation of neuronal precursor formation in Drosophila embryo. Development. 1994;120:935-45 pubmed
    ..da is not required for the initial appearance of nascent neuronal precursors but is required for these cells to express multiple neuronal precursor genes and to produce the normal number of neurons. ..
  12. Rusten T, Cantera R, Urban J, Technau G, Kafatos F, Barrio R. Spalt modifies EGFR-mediated induction of chordotonal precursors in the embryonic PNS of Drosophila promoting the development of oenocytes. Development. 2001;128:711-22 pubmed
  13. Lage P, Jan Y, Jarman A. Requirement for EGF receptor signalling in neural recruitment during formation of Drosophila chordotonal sense organ clusters. Curr Biol. 1997;7:166-75 pubmed
    ..The proneural gene atonal is required for the development of precursors of both chordotonal organs (stretch receptors) and photoreceptors...
  14. Baker N, Yu S. The EGF receptor defines domains of cell cycle progression and survival to regulate cell number in the developing Drosophila eye. Cell. 2001;104:699-708 pubmed
    ..Through proliferation and survival control, such signals couple the total number of uncommitted cells being generated to the neural patterning of the retina. ..
  15. Yang L, Baker N. Role of the EGFR/Ras/Raf pathway in specification of photoreceptor cells in the Drosophila retina. Development. 2001;128:1183-91 pubmed
    ..The results prove that R8 photoreceptors are specified and positioned by distinct mechanisms from photoreceptors R1-R7. ..
  16. Morey M, Yee S, Herman T, Nern A, Blanco E, Zipursky S. Coordinate control of synaptic-layer specificity and rhodopsins in photoreceptor neurons. Nature. 2008;456:795-9 pubmed publisher
  17. Niwa N, Hiromi Y, Okabe M. A conserved developmental program for sensory organ formation in Drosophila melanogaster. Nat Genet. 2004;36:293-7 pubmed
    ..In D. melanogaster, a common proneural gene called atonal (ato) functions in the initial process of development of a number of segment-specific organs, including the ..
  18. Baker N, Yu S. Proneural function of neurogenic genes in the developing Drosophila eye. Curr Biol. 1997;7:122-32 pubmed
    ..In the specific case of development of the Drosophila eye, expression of the proneural gene atonal is induced in response to Hedgehog signaling and then becomes subject to autoregulation...
  19. Jhaveri D, Rodrigues V. Sensory neurons of the Atonal lineage pioneer the formation of glomeruli within the adult Drosophila olfactory lobe. Development. 2002;129:1251-60 pubmed
    ..the basis of sensory targeting in the fruitfly Drosophila and show that one class of sensory neurons, those of the Atonal lineage, plays a crucial role in glomerular patterning...
  20. Eberl D. Feeling the vibes: chordotonal mechanisms in insect hearing. Curr Opin Neurobiol. 1999;9:389-93 pubmed
    ..Identification of these elusive molecules will settle this issue. ..
  21. Ben Arie N, Hassan B, Bermingham N, Malicki D, Armstrong D, Matzuk M, et al. Functional conservation of atonal and Math1 in the CNS and PNS. Development. 2000;127:1039-48 pubmed
    To determine the extent to which atonal and its mouse homolog Math1 exhibit functional conservation, we inserted (beta)-galactosidase (lacZ) into the Math1 locus and analyzed its expression, evaluated consequences of loss of Math1 ..
  22. Huang M, Hsu C, Chien C. The proneural gene amos promotes multiple dendritic neuron formation in the Drosophila peripheral nervous system. Neuron. 2000;25:57-67 pubmed
    ..amos encodes a basic-helix-loop-helix (bHLH) protein of the Atonal family...
  23. Penton A, Selleck S, Hoffmann F. Regulation of cell cycle synchronization by decapentaplegic during Drosophila eye development. Science. 1997;275:203-6 pubmed
    ..DPP may affect cell cycle synchronization by promoting cell cycle progression through the G2-M phases. This synchronization is critical for the precise assembly of the eye. ..
  24. zur Lage P, Jarman A. The function and regulation of the bHLH gene, cato, in Drosophila neurogenesis. BMC Dev Biol. 2010;10:34 pubmed publisher
    bHLH transcription factors play many roles in neural development. cousin of atonal (cato) encodes one such factor that is expressed widely in the developing sensory nervous system of Drosophila...
  25. zur Lage P, Powell L, Prentice D, McLaughlin P, Jarman A. EGF receptor signaling triggers recruitment of Drosophila sense organ precursors by stimulating proneural gene autoregulation. Dev Cell. 2004;7:687-96 pubmed publisher
    ..are selected by a recruitment pathway involving EGFR signaling to ectodermal cells expressing the proneural gene atonal. We show that EGFR signaling drives recruitment by directly facilitating atonal autoregulation...
  26. Vrailas A, Moses K. Smoothened, thickveins and the genetic control of cell cycle and cell fate in the developing Drosophila eye. Mech Dev. 2006;123:151-65 pubmed
    ..We conclude that both pathways have several, but differing roles in furrow induction and cell fate and survival, but that neither directly affects cell type specification. ..
  27. Goulding S, White N, Jarman A. cato encodes a basic helix-loop-helix transcription factor implicated in the correct differentiation of Drosophila sense organs. Dev Biol. 2000;221:120-31 pubmed
    ..gene, cato, which encodes a protein with a bHLH domain that is closely related to that of the proneural protein Atonal. cato expression is restricted to the developing PNS, where it is expressed in between the stages of precursor ..
  28. Sukhanova M, Deb D, Gordon G, Matakatsu M, Du W. Proneural basic helix-loop-helix proteins and epidermal growth factor receptor signaling coordinately regulate cell type specification and cdk inhibitor expression during development. Mol Cell Biol. 2007;27:2987-96 pubmed
    ..receptor signaling-regulated transcription factor Pointed (Pnt) and the proneural basic helix-loop-helix proteins Atonal (Ato) and Daughterless (Da)...
  29. Jiao R, Daube M, Duan H, Zou Y, Frei E, Noll M. Headless flies generated by developmental pathway interference. Development. 2001;128:3307-19 pubmed
  30. Lesokhin A, Yu S, Katz J, Baker N. Several levels of EGF receptor signaling during photoreceptor specification in wild-type, Ellipse, and null mutant Drosophila. Dev Biol. 1999;205:129-44 pubmed
    ..It is possible that during normal eye development these thresholds are attained by different cells, contributing to the pattern of retinal differentiation. ..
  31. Baker N. Cell proliferation, survival, and death in the Drosophila eye. Semin Cell Dev Biol. 2001;12:499-507 pubmed
    ..Reiterated episodes of cell death also contribute to precise regulation of retinal cell number. The EGF receptor homolog has multiple roles in retinal proliferation and survival. ..
  32. Chien C, Hsiao C, Jan L, Jan Y. Neuronal type information encoded in the basic-helix-loop-helix domain of proneural genes. Proc Natl Acad Sci U S A. 1996;93:13239-44 pubmed
    ..In Drosophila, two sets of proneural genes, atonal (ato) and members of the achaete-scute complex (ASC), are required for the formation of chordotonal (ch) organs ..
  33. Hassan B, Bermingham N, He Y, Sun Y, Jan Y, Zoghbi H, et al. atonal regulates neurite arborization but does not act as a proneural gene in the Drosophila brain. Neuron. 2000;25:549-61 pubmed
    Drosophila atonal (ato) is the proneural gene of the chordotonal organs (CHOs) in the peripheral nervous system (PNS) and the larval and adult photoreceptor organs...
  34. Wang V, Hassan B, Bellen H, Zoghbi H. Drosophila atonal fully rescues the phenotype of Math1 null mice: new functions evolve in new cellular contexts. Curr Biol. 2002;12:1611-6 pubmed
    ..We have been analyzing the relationship between atonal (ato) in the fruit fly and its mouse homolog, Math1...
  35. Zhang T, Ranade S, Cai C, Clouser C, Pignoni F. Direct control of neurogenesis by selector factors in the fly eye: regulation of atonal by Ey and So. Development. 2006;133:4881-9 pubmed
    ..or Retinal Determination (RD) network control specification of organ-type whereas the bHLH-type proneural factor Atonal drives neurogenesis...
  36. Maung S, Jarman A. Functional distinctness of closely related transcription factors: a comparison of the Atonal and Amos proneural factors. Mech Dev. 2007;124:647-56 pubmed
    ..paradigm of Drosophila sensory nervous system development, we examine the functional distinctness of the Amos and Atonal (Ato) proneural transcription factors, which have different mutant phenotypes but share very high similarity in ..
  37. Holohan E, zur Lage P, Jarman A. Multiple enhancers contribute to spatial but not temporal complexity in the expression of the proneural gene, amos. BMC Dev Biol. 2006;6:53 pubmed
    ..In the study of the Drosophila proneural genes, scute and atonal, several themes have emerged that contribute to our understanding of the mechanism of neurogenesis...
  38. Sen A, Kuruvilla D, Pinto L, Sarin A, Rodrigues V. Programmed cell death and context dependent activation of the EGF pathway regulate gliogenesis in the Drosophila olfactory system. Mech Dev. 2004;121:65-78 pubmed
    In the Drosophila antenna, sensory lineages selected by the basic helix-loop-helix transcription factor Atonal are gliogenic while those specified by the related protein Amos are not...
  39. Tomasi T, Hakeda Suzuki S, Ohler S, Schleiffer A, Suzuki T. The transmembrane protein Golden goal regulates R8 photoreceptor axon-axon and axon-target interactions. Neuron. 2008;57:691-704 pubmed publisher
    ..From detailed structure-function experiments, we propose that Gogo functions as a receptor that binds an unidentified ligand through its conserved extracellular domain. ..
  40. Jhaveri D, Sen A, Rodrigues V. Mechanisms underlying olfactory neuronal connectivity in Drosophila-the atonal lineage organizes the periphery while sensory neurons and glia pattern the olfactory lobe. Dev Biol. 2000;226:73-87 pubmed
    ..The glia originate from one of the three types of sensory lineages-specified by the proneural gene atonal. Gain-of-function as well as loss-of-function analysis validates a role for cells of the Atonal lineage in the ..
  41. Zheng X, Zugates C, Lu Z, Shi L, Bai J, Lee T. Baboon/dSmad2 TGF-beta signaling is required during late larval stage for development of adult-specific neurons. EMBO J. 2006;25:615-27 pubmed
    ..To better understand this process, we characterized the development of a dorsal cluster (DC) of Atonal-positive neurons that are born at early larval stages but do not undergo extensive morphogenesis until pupal ..
  42. Langen M, Koch M, Yan J, De Geest N, Erfurth M, Pfeiffer B, et al. Mutual inhibition among postmitotic neurons regulates robustness of brain wiring in Drosophila. elife. 2013;2:e00337 pubmed publisher
    ..DOI: ..
  43. Jarman A, Sun Y, Jan L, Jan Y. Role of the proneural gene, atonal, in formation of Drosophila chordotonal organs and photoreceptors. Development. 1995;121:2019-30 pubmed
    The Drosophila gene atonal encodes a basic helix-loop-helix protein similar to those encoded by the proneural genes of the achaete-scute complex (AS-C)...
  44. Caldwell J, Miller M, Wing S, Soll D, Eberl D. Dynamic analysis of larval locomotion in Drosophila chordotonal organ mutants. Proc Natl Acad Sci U S A. 2003;100:16053-8 pubmed
    ..We analyzed mutants carrying cho mutations including atonal, a cho proneural gene, beethoven, a cho cilia class mutant, smetana and touch-insensitive larva B, two axonemal ..
  45. Lai E. Drosophila tufted is a gain-of-function allele of the proneural gene amos. Genetics. 2003;163:1413-25 pubmed
    ..This phenomenon seems instead to be related to their shared ability to activate Asense and Senseless. ..
  46. Jarman A, Grell E, Ackerman L, Jan L, Jan Y. Atonal is the proneural gene for Drosophila photoreceptors. Nature. 1994;369:398-400 pubmed
    ..Here we show that atonal (ato), originally isolated as a proneural gene for chordotonal organs, is also the proneural gene for ..
  47. Dominguez M. Dual role for Hedgehog in the regulation of the proneural gene atonal during ommatidia development. Development. 1999;126:2345-53 pubmed
    ..The bHLH protein Atonal determines the development of the R8 cells...
  48. White N, Jarman A. Drosophila atonal controls photoreceptor R8-specific properties and modulates both receptor tyrosine kinase and Hedgehog signalling. Development. 2000;127:1681-9 pubmed
    During Drosophila eye development, the proneural gene atonal specifies founding R8 photoreceptors of individual ommatidia, evenly spaced relative to one another in a pattern that prefigures ommatidial organisation in the mature compound ..
  49. Tanaka Matakatsu M, Miller J, Borger D, Tang W, Du W. Daughterless homodimer synergizes with Eyeless to induce Atonal expression and retinal neuron differentiation. Dev Biol. 2014;392:256-65 pubmed publisher
    ..manuscript, we show that a linked dimer of Daughterless (Da), the only Drosophila class I bHLH protein, activates Atonal (Ato) expression and retinal neuron differentiation synergistically with the retinal determination factor Eyeless (..
  50. Ostrin E, Li Y, Hoffman K, Liu J, Wang K, Zhang L, et al. Genome-wide identification of direct targets of the Drosophila retinal determination protein Eyeless. Genome Res. 2006;16:466-76 pubmed
    ..of wild-type versus ectopic ey-expressing tissue, followed by microarray-based epistasis experiments in an atonal (ato) mutant background, identified 188 genes induced by ey...
  51. Jan Y, Jan L. Neuronal cell fate specification in Drosophila. Curr Opin Neurobiol. 1994;4:8-13 pubmed
    ..Selective expression of certain neuronal-type selector genes further specifies the type of neuron(s) that a neural precursor will produce. ..
  52. Nolo R, Abbott L, Bellen H. Senseless, a Zn finger transcription factor, is necessary and sufficient for sensory organ development in Drosophila. Cell. 2000;102:349-62 pubmed
    ..Sens is then in turn required to further activate and maintain proneural gene expression. This feedback mechanism is essential for selective enhancement and maintenance of proneural gene expression in the SOPs. ..
  53. Greenwood S, Struhl G. Progression of the morphogenetic furrow in the Drosophila eye: the roles of Hedgehog, Decapentaplegic and the Raf pathway. Development. 1999;126:5795-808 pubmed become proneural, a transition marked by downregulation of Hairy and upregulation of the proneural activator, Atonal (Ato), which initiates differentiation of the R8 photoreceptor...
  54. Tanaka Matakatsu M, Du W. Direct control of the proneural gene atonal by retinal determination factors during Drosophila eye development. Dev Biol. 2008;313:787-801 pubmed
    ..The proneural gene atonal (ato) encodes a basic-HLH protein required for photoreceptor and chordotonal organ formation...
  55. Baker N, Yu S, Han D. Evolution of proneural atonal expression during distinct regulatory phases in the developing Drosophila eye. Curr Biol. 1996;6:1290-301 pubmed
    ..In the Drosophila eye, Notch antagonises the basic helix-loop-helix (bHLH) protein atonal, which is required for R8 photoreceptor determination...
  56. Frankfort B, Nolo R, Zhang Z, Bellen H, Mardon G. senseless repression of rough is required for R8 photoreceptor differentiation in the developing Drosophila eye. Neuron. 2001;32:403-14 pubmed
    ..A genetic model of R8 differentiation is presented. ..
  57. Lai E, Orgogozo V. A hidden program in Drosophila peripheral neurogenesis revealed: fundamental principles underlying sensory organ diversity. Dev Biol. 2004;269:1-17 pubmed
    ..We propose that most Drosophila sensory organs are built from an archetypal lineage, and we speculate about how this stereotyped pattern of cell divisions may have been built during evolution...
  58. Jhaveri D, Sen A, Reddy G, Rodrigues V. Sense organ identity in the Drosophila antenna is specified by the expression of the proneural gene atonal. Mech Dev. 2000;99:101-11 pubmed
    We have shown that the basic helix-loop-helix transcription factor Atonal is sufficient for specification of one of the three subsets of olfactory sense organs on the Drosophila antenna...
  59. Cachero S, Simpson T, zur Lage P, Ma L, Newton F, Holohan E, et al. The gene regulatory cascade linking proneural specification with differentiation in Drosophila sensory neurons. PLoS Biol. 2011;9:e1000568 pubmed publisher
    ..High-resolution temporal profiling of gene expression reveals the events downstream of atonal proneural gene function during the development of Drosophila chordotonal (mechanosensory) neurons...
  60. Escudero L, Caminero E, Schulze K, Bellen H, Modolell J. Charlatan, a Zn-finger transcription factor, establishes a novel level of regulation of the proneural achaete/scute genes of Drosophila. Development. 2005;132:1211-22 pubmed
    ..chn is also required for the proper development of the embryonic peripheral nervous system, as its absence leads to loss of neurons and causes aberrant development of chordotonal organs. ..
  61. Elstob P, Brodu V, Gould A. spalt-dependent switching between two cell fates that are induced by the Drosophila EGF receptor. Development. 2001;128:723-32 pubmed
    ..Together, these studies help to explain how one generic signaling pathway can trigger the differentiation of two distinct cell types. ..
  62. Goulding S, zur Lage P, Jarman A. amos, a proneural gene for Drosophila olfactory sense organs that is regulated by lozenge. Neuron. 2000;25:69-78 pubmed
    ..For the Drosophila PNS, such transcription factors are encoded by the proneural genes (atonal and the achaete-scute complex, AS-C)...
  63. Fu W, Baker N. Deciphering synergistic and redundant roles of Hedgehog, Decapentaplegic and Delta that drive the wave of differentiation in Drosophila eye development. Development. 2003;130:5229-39 pubmed
    ..Notch acted in part through downregulation of Hairy; Hh signaling downregulated Hairy independently of Notch. One feature of this signaling network is to limit Dpp signaling spatially to a range coincident with Hh. ..
  64. Daniel A, Dumstrei K, Lengyel J, Hartenstein V. The control of cell fate in the embryonic visual system by atonal, tailless and EGFR signaling. Development. 1999;126:2945-54 pubmed
    We describe here the role of the transcription factors encoding genes tailless (tll), atonal (ato), sine oculis (so), eyeless (ey) and eyes absent (eya), and EGFR signaling in establishing the Drosophila embryonic visual system...