Gene Symbol: Shh
Description: sonic hedgehog
Alias: 9530036O11Rik, Dsh, Hhg1, Hxl3, M100081, ShhNC, sonic hedgehog protein, HHG-1, hemimelic extra toes, shh unprocessed N-terminal signaling and C-terminal autoprocessing domains, short digits
Species: mouse
Products:     Shh

Top Publications

  1. Cornett B, Snowball J, Varisco B, Lang R, Whitsett J, Sinner D. Wntless is required for peripheral lung differentiation and pulmonary vascular development. Dev Biol. 2013;379:38-52 pubmed publisher
    ..We generated conditional Wls mutant mice utilizing Shh-Cre and Dermo1-Cre mice to delete Wls in the embryonic respiratory epithelium and mesenchyme, respectively...
  2. Soshnikova N, Dewaele R, Janvier P, Krumlauf R, Duboule D. Duplications of hox gene clusters and the emergence of vertebrates. Dev Biol. 2013;378:194-9 pubmed publisher
  3. Kietzman H, Everson J, Sulik K, Lipinski R. The teratogenic effects of prenatal ethanol exposure are exacerbated by Sonic Hedgehog or GLI2 haploinsufficiency in the mouse. PLoS ONE. 2014;9:e89448 pubmed publisher
    ..Single allele mutations in the Hh pathway genes Sonic Hedgehog (SHH) and GLI2 cause holoprosencephaly with extremely variable phenotypic penetrance in humans...
  4. Sánchez Arrones L, Nieto Lopez F, Sánchez Camacho C, Carreres M, Herrera E, Okada A, et al. Shh/Boc signaling is required for sustained generation of ipsilateral projecting ganglion cells in the mouse retina. J Neurosci. 2013;33:8596-607 pubmed publisher
    Sonic Hedgehog (Shh) signaling is an important determinant of vertebrate retinal ganglion cell (RGC) development...
  5. Symmons O, Uslu V, Tsujimura T, Ruf S, Nassari S, Schwarzer W, et al. Functional and topological characteristics of mammalian regulatory domains. Genome Res. 2014;24:390-400 pubmed publisher
    ..These findings support a model of genomic organization where TADs confine regulatory activities to specific but large regulatory domains, contributing to the establishment of specific gene expression profiles. ..
  6. Liu H, Ermilov A, Grachtchouk M, Li L, Gumucio D, Dlugosz A, et al. Multiple Shh signaling centers participate in fungiform papilla and taste bud formation and maintenance. Dev Biol. 2013;382:82-97 pubmed publisher
    ..b>Shh signaling has established roles in supporting fungiform induction, development and patterning...
  7. Tsukiji N, Amano T, Shiroishi T. A novel regulatory element for Shh expression in the lung and gut of mouse embryos. Mech Dev. 2014;131:127-36 pubmed publisher
    ..In the mouse embryo, Sonic hedgehog (Shh) is expressed in endodermal epithelia from the oral cavity to the intestine, and contributes to cell proliferation ..
  8. Yang J, Brown A, Ellisor D, Paul E, Hagan N, Zervas M. Dynamic temporal requirement of Wnt1 in midbrain dopamine neuron development. Development. 2013;140:1342-52 pubmed publisher
    ..Collectively, our analyses resolve the spatial and temporal function of Wnt1 in Mb and Cb patterning and in MbDA neuron development in vivo. ..
  9. Lin C, Yin Y, Bell S, Veith G, Chen H, Huh S, et al. Delineating a conserved genetic cassette promoting outgrowth of body appendages. PLoS Genet. 2013;9:e1003231 pubmed publisher
    ..These observations indicate that a conserved WNT-SP8-FGF8 genetic cassette is employed by both appendages for promoting outgrowth, and suggest a deep homology shared by the limb and external genitalia. ..

More Information


  1. Andersson E, Salto C, Villaescusa J, Cajanek L, Yang S, Bryjova L, et al. Wnt5a cooperates with canonical Wnts to generate midbrain dopaminergic neurons in vivo and in stem cells. Proc Natl Acad Sci U S A. 2013;110:E602-10 pubmed publisher
  2. Abdelhamed Z, Wheway G, Szymanska K, Natarajan S, Toomes C, Inglehearn C, et al. Variable expressivity of ciliopathy neurological phenotypes that encompass Meckel-Gruber syndrome and Joubert syndrome is caused by complex de-regulated ciliogenesis, Shh and Wnt signalling defects. Hum Mol Genet. 2013;22:1358-72 pubmed publisher
    ..exencephaly, and frontal/occipital encephalocele) that were associated with the loss of primary cilia, diminished Shh signalling and dorsalization of the caudal neural tube...
  3. Hayes L, Ralls S, Wang H, Ahn S. Duration of Shh signaling contributes to mDA neuron diversity. Dev Biol. 2013;374:115-26 pubmed publisher
    Sonic hedgehog (Shh) signaling is critical for various developmental processes including specification of the midbrain dopamine (mDA) neurons in the ventral mesencephalon (vMes)...
  4. Lagronova Churava S, Spoutil F, Vojtechova S, Lesot H, Peterka M, Klein O, et al. The dynamics of supernumerary tooth development are differentially regulated by Sprouty genes. J Exp Zool B Mol Dev Evol. 2013;320:307-20 pubmed publisher
    ..tooth development in Spry2 and Spry4 mutants by comparing morphogenesis, proliferation, apoptosis, size and Shh expression in the dental epithelium of MS and R2 rudiments...
  5. Berlivet S, Paquette D, Dumouchel A, Langlais D, Dostie J, Kmita M. Clustering of tissue-specific sub-TADs accompanies the regulation of HoxA genes in developing limbs. PLoS Genet. 2013;9:e1004018 pubmed publisher
    ..From an evolutionary standpoint, our data points to the convergent evolution of HoxA and HoxD regulation in the fin-to-limb transition, one of the major morphological innovations in vertebrates. ..
  6. Aoto K, Trainor P. Co-ordinated brain and craniofacial development depend upon Patched1/XIAP regulation of cell survival. Hum Mol Genet. 2015;24:698-713 pubmed publisher
    ..Thus, co-ordinated development of the brain and face is dependent in part upon XIAP mediation of Hh/Ptch1-regulated cell survival and apoptosis during embryogenesis. ..
  7. Desai T, Brownfield D, Krasnow M. Alveolar progenitor and stem cells in lung development, renewal and cancer. Nature. 2014;507:190-4 pubmed publisher
    ..We propose that local signals regulate AT2 stem-cell activity: a signal transduced by EGFR-KRAS controls self-renewal and is hijacked during oncogenesis, whereas another signal controls reprogramming to AT1 fate. ..
  8. Li D, Sakuma R, Vakili N, Mo R, Puviindran V, Deimling S, et al. Formation of proximal and anterior limb skeleton requires early function of Irx3 and Irx5 and is negatively regulated by Shh signaling. Dev Cell. 2014;29:233-40 pubmed publisher
    Limb skeletal pattern relies heavily on graded Sonic hedgehog (Shh) signaling. As a morphogen and growth cue, Shh regulates identities of posterior limb elements, including the ulna/fibula and digits 2 through 5...
  9. Goetz S, Liem K, Anderson K. The spinocerebellar ataxia-associated gene Tau tubulin kinase 2 controls the initiation of ciliogenesis. Cell. 2012;151:847-858 pubmed publisher
    ..We propose that cell-cycle regulators target TTBK2 to the basal body, where it modifies specific targets to initiate ciliogenesis. ..
  10. Khonsari R, Seppala M, Pradel A, Dutel H, Clément G, Lebedev O, et al. The buccohypophyseal canal is an ancestral vertebrate trait maintained by modulation in sonic hedgehog signaling. BMC Biol. 2013;11:27 pubmed publisher
    ..Polaris(fl/fl); Wnt1-Cre, Ofd1(-/-) and Kif3a(-/-) primary cilia mouse mutants have abnormal sonic hedgehog (Shh) signaling and all present with malformations of the anterior pituitary gland and midline structures of the ..
  11. Lettice L, Williamson I, Devenney P, Kilanowski F, Dorin J, Hill R. Development of five digits is controlled by a bipartite long-range cis-regulator. Development. 2014;141:1715-25 pubmed publisher
    ..of the highly conserved ZRS (also called MFCS1) cis-regulator responsible for the spatiotemporal control of Shh in the limb bud...
  12. Sheth R, Grégoire D, Dumouchel A, Scotti M, Pham J, Nemec S, et al. Decoupling the function of Hox and Shh in developing limb reveals multiple inputs of Hox genes on limb growth. Development. 2013;140:2130-8 pubmed publisher
    ..ectodermal ridge (AER-FGFs), the maintenance of which relies on a positive-feedback loop involving sonic hedgehog (Shh) and the BMP antagonist gremlin 1 (Grem1)...
  13. Hayes L, Zhang Z, Albert P, Zervas M, Ahn S. Timing of Sonic hedgehog and Gli1 expression segregates midbrain dopamine neurons. J Comp Neurol. 2011;519:3001-18 pubmed publisher
    ..Using genetic inducible fate mapping to mark the Sonic hedgehog (Shh) and Gli1 lineages at varying embryonic stages, we performed a quantitative and qualitative comparison of the two ..
  14. Seidel K, Ahn C, Lyons D, Nee A, Ting K, Brownell I, et al. Hedgehog signaling regulates the generation of ameloblast progenitors in the continuously growing mouse incisor. Development. 2010;137:3753-61 pubmed publisher
    ..genetic lineage tracing to identify Hh-responsive stem cells in the mouse incisor and we show that sonic hedgehog (SHH), which is produced by the differentiating progeny of the stem cells, signals to several regions of the incisor...
  15. Bulgakov O, Eggenschwiler J, Hong D, Anderson K, Li T. FKBP8 is a negative regulator of mouse sonic hedgehog signaling in neural tissues. Development. 2004;131:2149-59 pubmed
    Sonic hedgehog (SHH) is a secreted morphogen that regulates the patterning and growth of many tissues in the developing mouse embryo, including the central nervous system (CNS)...
  16. Dufort D, Schwartz L, Harpal K, Rossant J. The transcription factor HNF3beta is required in visceral endoderm for normal primitive streak morphogenesis. Development. 1998;125:3015-25 pubmed
    ..We show that such mutant embryos lack foregut and midgut endoderm. In addition, left-right asymmetry is affected in the mutant embryos. ..
  17. Lu Q, Yuk D, Alberta J, Zhu Z, Pawlitzky I, Chan J, et al. Sonic hedgehog--regulated oligodendrocyte lineage genes encoding bHLH proteins in the mammalian central nervous system. Neuron. 2000;25:317-29 pubmed
    ..border and adjacent to the floor plate, a source of the secreted signaling molecule Sonic hedgehog (Shh)...
  18. Larkins C, Aviles G, East M, Kahn R, Caspary T. Arl13b regulates ciliogenesis and the dynamic localization of Shh signaling proteins. Mol Biol Cell. 2011;22:4694-703 pubmed publisher
    ..Previously, we showed that mice lacking Arl13b have abnormal Sonic hedgehog (Shh) signaling; in this study, we show the dynamics of Shh signaling component localization to the cilium are disrupted ..
  19. Jin Y, Turcotte T, Crocker A, Han X, Yoon J. The canonical Wnt signaling activator, R-spondin2, regulates craniofacial patterning and morphogenesis within the branchial arch through ectodermal-mesenchymal interaction. Dev Biol. 2011;352:1-13 pubmed publisher
    ..Thus, our study identifies Rspo2 as a mesenchyme-derived factor that plays critical roles in regulating BA1 patterning and morphogenesis through ectodermal-mesenchymal interaction and a novel genetic factor for cleft palate. ..
  20. Kenney A, Cole M, Rowitch D. Nmyc upregulation by sonic hedgehog signaling promotes proliferation in developing cerebellar granule neuron precursors. Development. 2003;130:15-28 pubmed
    ..We report that sonic hedgehog (Shh) signaling upregulates expression of the proto-oncogene Nmyc in cultured cerebellar granule neuron precursors (..
  21. Gritli Linde A, Bei M, Maas R, Zhang X, Linde A, McMahon A. Shh signaling within the dental epithelium is necessary for cell proliferation, growth and polarization. Development. 2002;129:5323-37 pubmed
    Sonic hedgehog (Shh), a member of the mammalian Hedgehog (Hh) family, plays a key role during embryogenesis and organogenesis. Tooth development, odontogenesis, is governed by sequential and reciprocal epithelial-mesenchymal interactions...
  22. Jeong Y, El Jaick K, Roessler E, Muenke M, Epstein D. A functional screen for sonic hedgehog regulatory elements across a 1 Mb interval identifies long-range ventral forebrain enhancers. Development. 2006;133:761-72 pubmed
    The secreted protein sonic hedgehog (Shh) plays an integral role in forming the ventral midline of the vertebrate central nervous system (CNS)...
  23. Hall T, Porter J, Beachy P, Leahy D. A potential catalytic site revealed by the 1.7-A crystal structure of the amino-terminal signalling domain of Sonic hedgehog. Nature. 1995;378:212-6 pubmed
    ..7 A of the amino-terminal domain of murine Sonic hedgehog (Shh-N)...
  24. Joubert O, Nehmé R, Fleury D, De Rivoyre M, Bidet M, Polidori A, et al. Functional studies of membrane-bound and purified human Hedgehog receptor Patched expressed in yeast. Biochim Biophys Acta. 2009;1788:1813-21 pubmed publisher
    The Sonic Hedgehog (Shh) signalling pathway plays an important role both in embryonic development and in adult stem cell function...
  25. Lan Y, Jiang R. Sonic hedgehog signaling regulates reciprocal epithelial-mesenchymal interactions controlling palatal outgrowth. Development. 2009;136:1387-96 pubmed publisher
    ..Previous studies have implicated sonic hedgehog (Shh) as an important epithelial signal for regulating palatal growth...
  26. Mill P, Mo R, Hu M, Dagnino L, Rosenblum N, Hui C. Shh controls epithelial proliferation via independent pathways that converge on N-Myc. Dev Cell. 2005;9:293-303 pubmed
    b>Shh signaling induces proliferation of many cell types during development and disease, but how Gli transcription factors regulate these mitogenic responses remains unclear...
  27. Panman L, Galli A, Lagarde N, Michos O, Soete G, Zuniga A, et al. Differential regulation of gene expression in the digit forming area of the mouse limb bud by SHH and gremlin 1/FGF-mediated epithelial-mesenchymal signalling. Development. 2006;133:3419-28 pubmed
    ..We combine mouse genetics with experimental manipulation of signalling to analyze the kinetics by which the SHH morphogen and the BMP antagonist gremlin 1 (GREM1) control gene expression in the digit-forming mesenchyme of mouse ..
  28. Filosa S, Rivera Pérez J, Gomez A, Gansmuller A, Sasaki H, Behringer R, et al. Goosecoid and HNF-3beta genetically interact to regulate neural tube patterning during mouse embryogenesis. Development. 1997;124:2843-54 pubmed
    ..75. Loss of Sonic hedgehog (Shh) and HNF-3beta expression was observed in the notochord and ventral neural tube of these embryos...
  29. Miller L, Wert S, Clark J, Xu Y, Perl A, Whitsett J. Role of Sonic hedgehog in patterning of tracheal-bronchial cartilage and the peripheral lung. Dev Dyn. 2004;231:57-71 pubmed
    Sonic hedgehog (Shh) was conditionally deleted in respiratory epithelial cells of the embryonic lung in vivo. Deletion of Shh before embryonic day (E) 13.5 resulted in respiratory failure at birth...
  30. Washington Smoak I, Byrd N, Abu Issa R, Goddeeris M, Anderson R, Morris J, et al. Sonic hedgehog is required for cardiac outflow tract and neural crest cell development. Dev Biol. 2005;283:357-72 pubmed
    ..In this study, we focus on the defects in pharyngeal arch and cardiovascular patterning present in Sonic hedgehog (Shh) null mouse embryos...
  31. Balczerski B, Zakaria S, Tucker A, Borycki A, Koyama E, Pacifici M, et al. Distinct spatiotemporal roles of hedgehog signalling during chick and mouse cranial base and axial skeleton development. Dev Biol. 2012;371:203-14 pubmed publisher
    ..floor plate, it has been assumed that their development, like the axial skeleton, is dependent on Sonic hedgehog (Shh) and modulation of bone morphogenetic protein (Bmp) signalling...
  32. Okada A, Charron F, Morin S, Shin D, Wong K, Fabre P, et al. Boc is a receptor for sonic hedgehog in the guidance of commissural axons. Nature. 2006;444:369-73 pubmed
    In the spinal cord, sonic hedgehog (Shh) is secreted by the floor plate to control the generation of distinct classes of ventral neurons along the dorsoventral axis...
  33. Dessaud E, Ribes V, Balaskas N, Yang L, Pierani A, Kicheva A, et al. Dynamic assignment and maintenance of positional identity in the ventral neural tube by the morphogen sonic hedgehog. PLoS Biol. 2010;8:e1000382 pubmed publisher
    ..An example is Sonic hedgehog (Shh), which acts in several developing vertebrate tissues, including the central nervous system, to provide positional ..
  34. Varnat F, Zacchetti G, Ruiz i Altaba A. Hedgehog pathway activity is required for the lethality and intestinal phenotypes of mice with hyperactive Wnt signaling. Mech Dev. 2010;127:73-81 pubmed publisher
    ..Marker analyses suggest predominant paracrine signaling from rare Shh producing cells in the crypt's bottom to adjacent Gli1(+) mesenchymal cells in normal adult mice...
  35. Goss A, Tian Y, Tsukiyama T, Cohen E, Zhou D, Lu M, et al. Wnt2/2b and beta-catenin signaling are necessary and sufficient to specify lung progenitors in the foregut. Dev Cell. 2009;17:290-8 pubmed publisher
    ..Together, these data reveal that canonical Wnt2/2b signaling is required for the specification of lung endoderm progenitors in the developing foregut...
  36. Dai P, Shinagawa T, Nomura T, Harada J, Kaul S, Wadhwa R, et al. Ski is involved in transcriptional regulation by the repressor and full-length forms of Gli3. Genes Dev. 2002;16:2843-8 pubmed
    ..In contrast, Sonic hedgehog (Shh) signaling from the posterior zone of polarizing activity blocks Gli3 processing and then induces the expression of ..
  37. Zhao X, Zhang Z, Song Y, Zhang X, Zhang Y, Hu Y, et al. Transgenically ectopic expression of Bmp4 to the Msx1 mutant dental mesenchyme restores downstream gene expression but represses Shh and Bmp2 in the enamel knot of wild type tooth germ. Mech Dev. 2000;99:29-38 pubmed
    ..In contrast, overexpression of Bmp4 in the wild type molar mesenchyme down-regulated Shh and Bmp2 expression in the enamel knot, the putative signaling center for tooth patterning, but did not produce a ..
  38. Ko S, Chung I, Xu X, Oka S, Zhao H, Cho E, et al. Smad4 is required to regulate the fate of cranial neural crest cells. Dev Biol. 2007;312:435-47 pubmed
    ..Taken together, our data show that TGF-beta/BMP signals rely on Smad-dependent pathways in the ectomesenchyme to mediate epithelial-mesenchymal interactions that control craniofacial organogenesis...
  39. Treier M, Gleiberman A, O Connell S, Szeto D, McMahon J, McMahon A, et al. Multistep signaling requirements for pituitary organogenesis in vivo. Genes Dev. 1998;12:1691-704 pubmed
    ..from a ventral pituitary organizing center that forms at the boundary of a region of oral ectoderm in which Shh expression is selectively excluded...
  40. Park J, Zhang J, Moro A, Kushida M, Wegner M, Kim P. Regulation of Sox9 by Sonic Hedgehog (Shh) is essential for patterning and formation of tracheal cartilage. Dev Dyn. 2010;239:514-26 pubmed publisher
    We report that Sonic Hedgehog (Shh) regulates both formation and patterning of tracheal cartilage by controlling the expression pattern and level of the chondrogenic gene, Sox9...
  41. Zhao L, Zevallos S, Rizzoti K, Jeong Y, Lovell Badge R, Epstein D. Disruption of SoxB1-dependent Sonic hedgehog expression in the hypothalamus causes septo-optic dysplasia. Dev Cell. 2012;22:585-96 pubmed publisher
    ..We demonstrate here that mouse embryos lacking Sonic hedgehog (Shh) in the prospective hypothalamus exhibit key features of SOD, including pituitary hypoplasia and absence of the ..
  42. Matsumaru D, Haraguchi R, Miyagawa S, Motoyama J, Nakagata N, Meijlink F, et al. Genetic analysis of Hedgehog signaling in ventral body wall development and the onset of omphalocele formation. PLoS ONE. 2011;6:e16260 pubmed publisher ventral body wall formation and its malformation, we analyzed phenotypes of mouse mutants of Sonic hedgehog (Shh), GLI-Kruppel family member 3 (Gli3) and Aristaless-like homeobox 4 (Alx4)...
  43. Babbs C, Furniss D, Morriss Kay G, Wilkie A. Polydactyly in the mouse mutant Doublefoot involves altered Gli3 processing and is caused by a large deletion in cis to Indian hedgehog. Mech Dev. 2008;125:517-26 pubmed publisher
    ..5 is unaffected by the mutation. As both Sonic hedgehog (Shh) and Ihh expression are present in Dbf limb buds at E10...
  44. Cohen M, Shiota K. Teratogenesis of holoprosencephaly. Am J Med Genet. 2002;109:1-15 pubmed
  45. Hu M, Mo R, Bhella S, Wilson C, Chuang P, Hui C, et al. GLI3-dependent transcriptional repression of Gli1, Gli2 and kidney patterning genes disrupts renal morphogenesis. Development. 2006;133:569-78 pubmed
    Truncating mutations in Gli3, an intracellular effector in the SHH-SMO-GLI signaling pathway, cause renal aplasia/dysplasia in humans and mice. Yet, the pathogenic mechanisms are undefined...
  46. Zuniga A, Quillet R, Perrin Schmitt F, Zeller R. Mouse Twist is required for fibroblast growth factor-mediated epithelial-mesenchymal signalling and cell survival during limb morphogenesis. Mech Dev. 2002;114:51-9 pubmed
    ..In particular, the SHH/FGF signalling feedback loop operating between the polarizing region and the apical ectodermal ridge (AER) is ..
  47. Marin O, Baker J, Puelles L, Rubenstein J. Patterning of the basal telencephalon and hypothalamus is essential for guidance of cortical projections. Development. 2002;129:761-73 pubmed
    ..Furthermore, analysis of the expression of candidate molecules in the basal telencephalon and hypothalamus of Nkx2-1 mutants suggests that Slit2 contributes to this activity. ..
  48. Gonzalez Reyes L, Verbitsky M, Blesa J, Jackson Lewis V, Paredes D, Tillack K, et al. Sonic hedgehog maintains cellular and neurochemical homeostasis in the adult nigrostriatal circuit. Neuron. 2012;75:306-19 pubmed publisher
    ..We report that the interruption of a non cell-autonomous mode of sonic hedgehog (Shh) signaling originating from dopaminergic neurons causes progressive, adult-onset degeneration of dopaminergic, ..
  49. Okada T, Okumura Y, Motoyama J, Ogawa M. FGF8 signaling patterns the telencephalic midline by regulating putative key factors of midline development. Dev Biol. 2008;320:92-101 pubmed publisher
    ..Although FGF8 had been thought to act downstream of SHH signaling, ectopic FGF8 up-regulates the expression of midline TF genes in Shh null mice, suggesting that FGF ..
  50. Maretto S, Müller P, Aricescu A, Cho K, Bikoff E, Robertson E. Ventral closure, headfold fusion and definitive endoderm migration defects in mouse embryos lacking the fibronectin leucine-rich transmembrane protein FLRT3. Dev Biol. 2008;318:184-93 pubmed publisher
    ..Surprisingly, the mutation has no effect on FGF signalling. Collectively these experiments demonstrate that FLRT3 plays a key role in controlling cell adhesion and tissue morphogenesis in the developing mouse embryo. ..
  51. Yoshikawa Y, Fujimori T, McMahon A, Takada S. Evidence that absence of Wnt-3a signaling promotes neuralization instead of paraxial mesoderm development in the mouse. Dev Biol. 1997;183:234-42 pubmed
    ..These results suggest that Wnt-3a signaling may play a role in regulating paraxial mesodermal fates, at the expense of neurectodermal fates, within the primitive ectoderm of the gastrulating mouse embryo. ..
  52. Mukhopadhyay M, Shtrom S, Rodriguez Esteban C, Chen L, Tsukui T, Gomer L, et al. Dickkopf1 is required for embryonic head induction and limb morphogenesis in the mouse. Dev Cell. 2001;1:423-34 pubmed
  53. Outram S, Varas A, Pepicelli C, Crompton T. Hedgehog signaling regulates differentiation from double-negative to double-positive thymocyte. Immunity. 2000;13:187-97 pubmed
    ..The hedgehog (Hh) signaling pathway is involved in the development of many tissues. Here we show that sonic hedgehog (Shh) is involved in thymocyte development...