Gene Symbol: Con
Description: Connectin
Alias: CG7503, CON, CT1840, Dmel\CG7503, Ubx-t35, anon-64C, con, conn, connectin, CG7503-PA, CG7503-PB, Con-PA, Con-PB, transcript-35
Species: fruit fly
Products:     Con

Top Publications

  1. Ruiz Gomez M, Coutts N, Price A, Taylor M, Bate M. Drosophila dumbfounded: a myoblast attractant essential for fusion. Cell. 2000;102:189-98 pubmed
    ..duf encodes a member of the immunoglobulin superfamily of proteins that is an attractant for fusion-competent myoblasts. It is expressed by founder cells and serves to attract clusters of myoblasts from which myotubes form by fusion. ..
  2. Knirr S, Azpiazu N, Frasch M. The role of the NK-homeobox gene slouch (S59) in somatic muscle patterning. Development. 1999;126:4525-35 pubmed
    ..Together, these findings provide new insights into the regulatory interactions that establish the somatic muscle pattern. ..
  3. Nose A, Mahajan V, Goodman C. Connectin: a homophilic cell adhesion molecule expressed on a subset of muscles and the motoneurons that innervate them in Drosophila. Cell. 1992;70:553-67 pubmed small subsets of muscle fibers prior to innervation, and identified two of these as inserts in connectin and Toll, members of the leucine-rich repeat gene family...
  4. Martin B, Ruiz Gomez M, Landgraf M, Bate M. A distinct set of founders and fusion-competent myoblasts make visceral muscles in the Drosophila embryo. Development. 2001;128:3331-8 pubmed
    ..These specialisations are revealed in mutant embryos where myoblast fusion fails. In the absence of fusion, founders make mononucleate circular or longitudinal fibres, while their fusion-competent neighbours remain undifferentiated. ..
  5. Rushton E, Drysdale R, Abmayr S, Michelson A, Bate M. Mutations in a novel gene, myoblast city, provide evidence in support of the founder cell hypothesis for Drosophila muscle development. Development. 1995;121:1979-88 pubmed
    ..We suggest that this subset of myoblasts represents the proposed muscle founder cells and we draw an analogy between these founder cells and the muscle pioneers described for grasshopper muscle development. ..
  6. Meadows L, Gell D, Broadie K, Gould A, White R. The cell adhesion molecule, connectin, and the development of the Drosophila neuromuscular system. J Cell Sci. 1994;107 ( Pt 1):321-8 pubmed
    The connectin gene of Drosophila has been identified as a candidate direct target of homeotic gene control and has also been implicated in the formation of specific neuromuscular connections...
  7. Reed H, Hoare T, Thomsen S, Weaver T, White R, Akam M, et al. Alternative splicing modulates Ubx protein function in Drosophila melanogaster. Genetics. 2010;184:745-58 pubmed publisher
    ..Since other Hox genes also produce splicing isoforms affecting similar protein domains, we suggest that alternative splicing may represent an underestimated regulatory system modulating Hox gene specificity during fly development. ..
  8. Ratnaparkhi A, Banerjee S, Hasan G. Altered levels of Gq activity modulate axonal pathfinding in Drosophila. J Neurosci. 2002;22:4499-508 pubmed
  9. Friedrich J, Sorge S, Bujupi F, Eichenlaub M, Schulz N, Wittbrodt J, et al. Hox Function Is Required for the Development and Maintenance of the Drosophila Feeding Motor Unit. Cell Rep. 2016;14:850-860 pubmed publisher
    ..a potential regulator of synaptic specificity, as it represses expression of the synaptic cell adhesion molecule Connectin (Con)...

More Information


  1. Battye R, Stevens A, Jacobs J. Axon repulsion from the midline of the Drosophila CNS requires slit function. Development. 1999;126:2475-81 pubmed
    ..slit interacts genetically with roundabout, which encodes a putative receptor for growth cone repulsion. ..
  2. Lockwood W, Bodmer R. The patterns of wingless, decapentaplegic, and tinman position the Drosophila heart. Mech Dev. 2002;114:13-26 pubmed
    ..We conclude that ectopic heart can be generated by altering the patterns of wg and dpp within the tin-expressing mesoderm, or by ectopic induction of tin within the wg- and dpp-expressing ectoderm. ..
  3. 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
    ..The robo,robo2 double mutant is largely identical to slit. ..
  4. Chiba A. Early development of the Drosophila neuromuscular junction: a model for studying neuronal networks in development. Int Rev Neurobiol. 1999;43:1-24 pubmed
  5. Eisen J. Genetic and molecular analyses of motoneuron development. Curr Opin Neurobiol. 1998;8:697-704 pubmed
    ..Many of the same molecules participate in the guidance of both vertebrate and fly motor axons. It is less clear, however, whether the same molecular mechanisms establish vertebrate and fly motoneuron identities. ..
  6. Gould A, White R. Connectin, a target of homeotic gene control in Drosophila. Development. 1992;116:1163-74 pubmed
    ..This 110 bp fragment maps within a regulatory region of a gene under homeotic control, connectin. A 4 kb DNA fragment, including the immunopurified binding site, is sufficient to reproduce the appropriate ..
  7. Yan D, Wu Y, Feng Y, Lin S, Lin X. The core protein of glypican Dally-like determines its biphasic activity in wingless morphogen signaling. Dev Cell. 2009;17:470-81 pubmed publisher
    ..Based on these data, we propose that the principal function of Dlp is to retain Wg on the cell surface. As such, it can either compete with the receptor or provide ligands to the receptor, depending on the ratios of Wg, Fz2, and Dlp. ..
  8. Jurata L, Thomas J, Pfaff S. Transcriptional mechanisms in the development of motor control. Curr Opin Neurobiol. 2000;10:72-9 pubmed
  9. Hu S, Fambrough D, Atashi J, Goodman C, Crews S. The Drosophila abrupt gene encodes a BTB-zinc finger regulatory protein that controls the specificity of neuromuscular connections. Genes Dev. 1995;9:2936-48 pubmed
    ..Abrupt is expressed in muscle nuclei but not motoneurons, suggesting that abrupt controls the muscle expression of molecules required for correct motoneuron targeting, as well as molecules required for correct muscle attachments. ..
  10. Nose A, Umeda T, Takeichi M. Neuromuscular target recognition by a homophilic interaction of connectin cell adhesion molecules in Drosophila. Development. 1997;124:1433-41 pubmed
    Drosophila Connectin (CON) is a cell surface protein of the leucine-rich repeat family...
  11. San Martin B, Bate M. Hindgut visceral mesoderm requires an ectodermal template for normal development in Drosophila. Development. 2001;128:233-42 pubmed
    ..Wingless is required to establish the primordium and to enhance Heartless expression. Later, Heartless is required to promote the proper differentiation of the hindgut visceral mesoderm itself. ..
  12. Milan M, Weihe U, Perez L, Cohen S. The LRR proteins capricious and Tartan mediate cell interactions during DV boundary formation in the Drosophila wing. Cell. 2001;106:785-94 pubmed
  13. Bilder D, Scott M. Hedgehog and wingless induce metameric pattern in the Drosophila visceral mesoderm. Dev Biol. 1998;201:43-56 pubmed
    ..As VM progenitors merge to form a continuous band running anterior to posterior along the embryo, expression of connectin (con) in 11 metameric patches within the VM reveals VM subdivisions analagous to ectodermal compartments...
  14. Botas J. Control of morphogenesis and differentiation by HOM/Hox genes. Curr Opin Cell Biol. 1993;5:1015-22 pubmed
    ..Some of the genes they regulate and that mediate specific identify functions have been identified. Research in Drosophila has shown that HOM genes are continuously required during development for correct axial identity. ..
  15. Okumura T, Fujiwara H, Taniguchi K, Kuroda J, Nakazawa N, Nakamura M, et al. Left-right asymmetric morphogenesis of the anterior midgut depends on the activation of a non-muscle myosin II in Drosophila. Dev Biol. 2010;344:693-706 pubmed publisher
    ..Taken together with previous studies in vertebrates, the involvement of myosin II in LR asymmetric morphogenesis might be conserved evolutionarily. ..
  16. Andrews G, Tanglao S, Farmer W, Morin S, Brotman S, Berberoglu M, et al. Dscam guides embryonic axons by Netrin-dependent and -independent functions. Development. 2008;135:3839-48 pubmed publisher
    ..These functions in axon guidance have implications for the pathogenesis of Down Syndrome. ..
  17. Liu X, Kiss I, Lengyel J. Identification of genes controlling malpighian tubule and other epithelial morphogenesis in Drosophila melanogaster. Genetics. 1999;151:685-95 pubmed
    ..Finally, from the same screen, we identified a second novel gene, drumstick, that affects only foregut and hindgut morphogenesis. ..
  18. 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
  19. Takemura S, Karuppudurai T, Ting C, Lu Z, Lee C, Meinertzhagen I. Cholinergic circuits integrate neighboring visual signals in a Drosophila motion detection pathway. Curr Biol. 2011;21:2077-84 pubmed publisher
    ..We propose that Tm2 integrates sign-conserving inputs from neighboring columns to mediate the detection of front-to-back motion generated during forward motion. ..
  20. Packard M, Mathew D, Budnik V. FASt remodeling of synapses in Drosophila. Curr Opin Neurobiol. 2003;13:527-34 pubmed
    ..These studies offer convincing evidence that synaptic cell adhesion brings about both negative and positive forces that stabilize synapses, while maintaining their ability to change in an activity-dependent manner. ..
  21. Hozumi S, Maeda R, Taniguchi Kanai M, Okumura T, Taniguchi K, Kawakatsu Y, et al. Head region of unconventional myosin I family members is responsible for the organ-specificity of their roles in left-right polarity in Drosophila. Dev Dyn. 2008;237:3528-37 pubmed publisher
    ..Our results also suggest that the organ specificities of the Myo31DF and Myo61F activities depended on their head regions. ..
  22. Keynes R, Cook G. Axon guidance molecules. Cell. 1995;83:161-9 pubmed
  23. Nose A, Van Vactor D, Auld V, Goodman C. Development of neuromuscular specificity in Drosophila. Cold Spring Harb Symp Quant Biol. 1992;57:441-9 pubmed
  24. Garrity P, Zipursky S. Neuronal target recognition. Cell. 1995;83:177-85 pubmed
  25. Umemiya T, Takeichi M, Nose A. M-spondin, a novel ECM protein highly homologous to vertebrate F-spondin, is localized at the muscle attachment sites in the Drosophila embryo. Dev Biol. 1997;186:165-76 pubmed
    ..We propose that M-spondin, although its function is redundant, is a component of the ECM and mediates mechanical linkage between the muscles and apodemes. ..
  26. Wolf B, Seeger M, Chiba A. Commissureless endocytosis is correlated with initiation of neuromuscular synaptogenesis. Development. 1998;125:3853-63 pubmed
    ..We propose that COMM is an essential part of the dynamic cell surface remodeling needed by postsynaptic cells in coordinating synaptogenesis initiation. ..
  27. Yu H, Huang A, Kolodkin A. Semaphorin-1a acts in concert with the cell adhesion molecules fasciclin II and connectin to regulate axon fasciculation in Drosophila. Genetics. 2000;156:723-31 pubmed
    ..Here, by manipulating the levels of Sema-1a and the cell adhesion molecules fasciclin II (Fas II) and connectin (Conn) on motor axons, we provide further evidence that Sema-1a mediates axonal defasciculation events by acting ..
  28. Newquist G, Drennan J, Lamanuzzi M, Walker K, Clemens J, Kidd T. Blocking apoptotic signaling rescues axon guidance in Netrin mutants. Cell Rep. 2013;3:595-606 pubmed publisher
    ..In contrast to the traditional role of Netrin as simply a guidance cue, our results demonstrate that guidance and survival activities may be functionally related. ..
  29. Bilder D, Graba Y, Scott M. Wnt and TGFbeta signals subdivide the AbdA Hox domain during Drosophila mesoderm patterning. Development. 1998;125:1781-90 pubmed
    ..pnt activation is required to determine the appropriate numbers of mesodermal cells in the third midgut chamber. ..
  30. Ruiz Gomez M. Muscle patterning and specification in Drosophila. Int J Dev Biol. 1998;42:283-90 pubmed
  31. Johansen K, Iwaki D, Lengyel J. Localized JAK/STAT signaling is required for oriented cell rearrangement in a tubular epithelium. Development. 2003;130:135-45 pubmed
    ..These results provide the first example in which JAK/STAT signaling plays a required role in orienting cell rearrangement that elongates an epithelium. ..
  32. Bate M, Broadie K. Wiring by fly: the neuromuscular system of the Drosophila embryo. Neuron. 1995;15:513-25 pubmed
  33. Ting C, McQueen P, Pandya N, Lin T, Yang M, Reddy O, et al. Photoreceptor-derived activin promotes dendritic termination and restricts the receptive fields of first-order interneurons in Drosophila. Neuron. 2014;81:830-846 pubmed publisher
    ..We suggest that afferent-derived Activin regulates the dendritic field size of their postsynaptic partners to ensure appropriate synaptic partnership. ..
  34. Certel S, Clyne P, Carlson J, Johnson W. Regulation of central neuron synaptic targeting by the Drosophila POU protein, Acj6. Development. 2000;127:2395-405 pubmed
    ..Our results suggest that the class IV POU domain factor, Acj6, may play an important role in regulating synaptic target selection by central neurons and that the amino-terminal POU IV box is important for regulation of Acj6 activity. ..
  35. Jakobsen J, Braun M, Astorga J, Gustafson E, Sandmann T, Karzynski M, et al. Temporal ChIP-on-chip reveals Biniou as a universal regulator of the visceral muscle transcriptional network. Genes Dev. 2007;21:2448-60 pubmed
    ..The regulatory connection of a number of Biniou target genes is conserved in mice, suggesting an ancient wiring of this developmental program. ..
  36. Panàkovà D, Sprong H, Marois E, Thiele C, Eaton S. Lipoprotein particles are required for Hedgehog and Wingless signalling. Nature. 2005;435:58-65 pubmed
    ..Similarly, the range of Wingless signalling is narrowed. We propose a novel function for lipoprotein particles, in which they act as vehicles for the movement of lipid-linked morphogens and glycophosphatidylinositol-linked proteins. ..
  37. Johansen K, Green R, Iwaki D, Hernandez J, Lengyel J. The Drm-Bowl-Lin relief-of-repression hierarchy controls fore- and hindgut patterning and morphogenesis. Mech Dev. 2003;120:1139-51 pubmed
    ..Since the odd-family and lin are conserved in mosquito, mouse, and humans, we propose that the odd-family genes and lin may also interact to control patterning and morphogenesis in other insects and in vertebrates. ..
  38. Baines R, Seugnet L, Thompson A, Salvaterra P, Bate M. Regulation of synaptic connectivity: levels of Fasciclin II influence synaptic growth in the Drosophila CNS. J Neurosci. 2002;22:6587-95 pubmed
    ..This effect of Fas II is isoform specific and, moreover, phenocopies the disruption to synaptic connectivity observed previously after tetanus toxin light chain-dependent blockade of evoked synaptic vesicle release in these neurons. ..
  39. Raghavan S, White R. Connectin mediates adhesion in Drosophila. Neuron. 1997;18:873-80 pubmed
    The Drosophila cell-surface molecule connectin mediates cell-cell adhesion in vitro, and its expression pattern in vivo fits well with an adhesion role in the embryonic neuromuscular system...
  40. Yan D, Wu Y, Yang Y, Belenkaya T, Tang X, Lin X. The cell-surface proteins Dally-like and Ihog differentially regulate Hedgehog signaling strength and range during development. Development. 2010;137:2033-44 pubmed publisher
    ..However, Ihog might not act as a classic co-receptor; rather, it may act as an exchange factor by retaining Hh on the cell surface, but also compete with the receptor for Hh binding. ..
  41. Hoang B, Chiba A. 'Identify' and 'lock in': molecular integration during synaptic target recognition. Cell Mol Life Sci. 1999;55:1399-406 pubmed
    ..We present a theoretical framework for understanding synaptic target recognition and discuss the features of its molecular components and their integration, drawing on the rapid progress made in recent studies. ..
  42. Ghavi Helm Y, Klein F, Pakozdi T, Ciglar L, Noordermeer D, Huber W, et al. Enhancer loops appear stable during development and are associated with paused polymerase. Nature. 2014;512:96-100 pubmed publisher
    ..Our results indicate that the general topology governing enhancer contacts is conserved from flies to humans and suggest that transcription initiates from preformed enhancer-promoter loops through release of paused polymerase. ..
  43. Karuppudurai T, Lin T, Ting C, Pursley R, Melnattur K, Diao F, et al. A hard-wired glutamatergic circuit pools and relays UV signals to mediate spectral preference in Drosophila. Neuron. 2014;81:603-615 pubmed publisher
    ..We conclude that R7s→Dm8→Tm5c form a hard-wired glutamatergic circuit that mediates UV preference by pooling ∼16 R7 signals for transfer to the lobula, a higher visual center. ..
  44. Hughes S, Salinas P. Control of muscle fibre and motoneuron diversification. Curr Opin Neurobiol. 1999;9:54-64 pubmed
    ..We propose a model in which four classes of decision control the patterning of both motoneurons and muscles. ..
  45. Callahan C, Muralidhar M, Lundgren S, Scully A, Thomas J. Control of neuronal pathway selection by a Drosophila receptor protein-tyrosine kinase family member. Nature. 1995;376:171-4 pubmed
    ..In drl mutant embryos these neurons fail to make the correct pathway choices. Our results provide evidence for receptor protein-tyrosine kinase involvement in key aspects of neuronal pathway recognition. ..
  46. Broadie K, Bate M. Innervation directs receptor synthesis and localization in Drosophila embryo synaptogenesis. Nature. 1993;361:350-3 pubmed
    ..We conclude that the muscle autonomously defines the synaptic site, whereas the motor neuron directs the development of the muscle's receptive field by stimulating the synthesis and localization of transmitter receptors. ..
  47. Iwaki D, Johansen K, Singer J, Lengyel J. drumstick, bowl, and lines are required for patterning and cell rearrangement in the Drosophila embryonic hindgut. Dev Biol. 2001;240:611-26 pubmed
    ..The close association of both cell rearrangement and patterning defects in all three mutants suggest that proper patterning of the hindgut into small intestine and large intestine is likely required for its correct morphogenesis. ..
  48. Siegler M, Jia X. Engrailed negatively regulates the expression of cell adhesion molecules connectin and neuroglian in embryonic Drosophila nervous system. Neuron. 1999;22:265-76 pubmed
    Engrailed is expressed in subsets of interneurons that do not express Connectin or appreciable Neuroglian, whereas other neurons that are Engrailed negative strongly express these adhesion molecules...
  49. Carrasco Rando M, Ruiz Gomez M. Mind bomb 2, a founder myoblast-specific protein, regulates myoblast fusion and muscle stability. Development. 2008;135:849-57 pubmed publisher
    ..We suggest that Mib2 acts sequentially in myoblast fusion and sarcomeric stability by two separable processes involving distinct functions of Mib2. ..
  50. Morata G. Homeotic genes of Drosophila. Curr Opin Genet Dev. 1993;3:606-14 pubmed
    ..Comparison between Drosophila and other species suggests a common functional organization of homeotic complexes in the animal kingdom. ..
  51. Kuang B, Wu S, Shin Y, Luo L, Kolodziej P. split ends encodes large nuclear proteins that regulate neuronal cell fate and axon extension in the Drosophila embryo. Development. 2000;127:1517-29 pubmed
    ..We propose that Spen proteins regulate the expression of key effectors of signaling pathways required to specify neuronal cell fate and morphology. ..
  52. De Velasco B, Mandal L, Mkrtchyan M, Hartenstein V. Subdivision and developmental fate of the head mesoderm in Drosophila melanogaster. Dev Genes Evol. 2006;216:39-51 pubmed
    ..The lSHM contributes hemocytes, as well as the nephrocytes forming the subesophageal body, also called garland cells. ..
  53. Sun Q, Bahri S, Schmid A, Chia W, Zinn K. Receptor tyrosine phosphatases regulate axon guidance across the midline of the Drosophila embryo. Development. 2000;127:801-12 pubmed
  54. Baylies M, Bate M, Ruiz Gomez M. The specification of muscle in Drosophila. Cold Spring Harb Symp Quant Biol. 1997;62:385-93 pubmed
  55. Hosono C, Takaira K, Matsuda R, Saigo K. Functional subdivision of trunk visceral mesoderm parasegments in Drosophila is required for gut and trachea development. Development. 2003;130:439-49 pubmed
    ..It has been demonstrated that the trunk visceral mesoderm parasegment is subdivided into at least two domains by connectin expression, which is regulated by Hedgehog and Wingless emanating from the ectoderm...
  56. He H, Noll M. Differential and redundant functions of gooseberry and gooseberry neuro in the central nervous system and segmentation of the Drosophila embryo. Dev Biol. 2013;382:209-23 pubmed publisher
    ..A model is proposed how selection for both genes occurred after their duplication during evolution. ..
  57. Gibert J. The evolution of engrailed genes after duplication and speciation events. Dev Genes Evol. 2002;212:307-18 pubmed
    ..However, in all engrailed duplications studied, even in ancient chromosomal duplications, the paralogues have kept redundant functions. In fact, selection seems to maintain a certain redundancy between engrailed paralogues. ..
  58. Landgraf M, Roy S, Prokop A, Vijayraghavan K, Bate M. even-skipped determines the dorsal growth of motor axons in Drosophila. Neuron. 1999;22:43-52 pubmed
    ..Thus, even-skipped complements the function of islet, and together these two genes constitute a bimodal switch regulating axonal growth and directing motor axons to ventral or to dorsal regions of the muscle field. ..
  59. Fambrough D, Goodman C. The Drosophila beaten path gene encodes a novel secreted protein that regulates defasciculation at motor axon choice points. Cell. 1996;87:1049-58 pubmed
    ..This phenotype is suppressed by mutations in FasII and conn, two genes encoding cell adhesion molecules expressed on motor axons, suggesting that beat provides an antiadhesive ..
  60. 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
    ..The levels of Comm and Robo appear to be tightly regulated to assure that only certain growth cones cross the midline and that those growth cones that do cross never do so again. ..
  61. Kidd T, Bland K, Goodman C. Slit is the midline repellent for the robo receptor in Drosophila. Cell. 1999;96:785-94 pubmed
    ..Slit appears to function as a short-range repellent controlling axon crossing of the midline and as a long-range chemorepellent controlling mesoderm migration away from the midline. ..
  62. Tear G. Neuronal guidance. A genetic perspective. Trends Genet. 1999;15:113-8 pubmed
    ..Here I highlight the part genetic screens and analyses have played in revealing some of the key players in neuronal guidance. ..
  63. White R, Brookman J, Gould A, Meadows L, Shashidhara L, Strutt D, et al. Targets of homeotic gene regulation in Drosophila. J Cell Sci Suppl. 1992;16:53-60 pubmed
    ..The chromatin immunopurification strategy may be of general application for the identification of direct in vivo targets of DNA-binding proteins. ..
  64. Carrasco Rando M, Tutor A, Prieto Sánchez S, González Pérez E, Barrios N, Letizia A, et al. Drosophila araucan and caupolican integrate intrinsic and signalling inputs for the acquisition by muscle progenitors of the lateral transverse fate. PLoS Genet. 2011;7:e1002186 pubmed publisher
    ..This provides a comprehensive insight into the way Iroquois genes integrate in muscle progenitors, signalling inputs that modulate gene expression and protein activity. ..
  65. Lee S, Harris K, Whitington P, Kolodziej P. short stop is allelic to kakapo, and encodes rod-like cytoskeletal-associated proteins required for axon extension. J Neurosci. 2000;20:1096-108 pubmed
    ..shot is allelic to kakapo, a gene that may function in integrin-mediated adhesion in the wing and embryo. We propose that Shot's interactions with the actin cytoskeleton allow sensory and motor axons to extend. ..
  66. Shishido E, Ono N, Kojima T, Saigo K. Requirements of DFR1/Heartless, a mesoderm-specific Drosophila FGF-receptor, for the formation of heart, visceral and somatic muscles, and ensheathing of longitudinal axon tracts in CNS. Development. 1997;124:2119-28 pubmed
    ..DFR1 mutant phenotypes were partially mimicked by the targeted expression of activated Yan, thus demonstrating the MAP kinase pathway to be involved in differentiation of mesoderm. ..