Hahn M, Jaeckle H (1996) Drosophila goosecoid participates in neural development but not in body axis formation. EMBO J 15: 3077–3084 Hartwell KA, Muir B, Reinhardt F, Carpenter AE, Sgroi DC, Weinberg RA (2006) The Spemann organizer gene, Goosecoid, promotes tumor metastasis. Proc Natl Acad Sci USA 103: 18969–18974 Heasman J (2002) Morpholino oligos: making sense of antisense? Dev Biol 243: 209–214 Henningfeld KA, Friedle H, Rastegar S, Kno¨chel W (2002) Autoregulation of Xvent-2B; direct interaction and functional cooperation of Xvent-2 and Smad1. J Biol Chem 277: 2097–2103 Imai Y, Gates MA, Melby AE, Kimelman D, Schier AF, Talbot WS (2001) The homeobox genes vox and vent are redundant repres- sors of dorsal fates in zebraﬁsh. Development 128: 2407–2420 Kappen C, Schughart K, Ruddle FH (1993) Early evolutionary origin of major homeodomain sequence classes. Genomics 18: 54–70 Karaulanov E, Knoechel W, Niehrs C (2004) Transcriptional regula- tion of BMP4 synexpression in transgenic Xenopus. EMBO J 23: 844–856 Kawahara A, Wilm T, Solnica-Krezel L, Dawid IB (2000a) Antagonistic role of vega1 and bozozok/dharma homeobox genes in organizer formation. Proc Natl Acad Sci USA 97: 12121–12126 Kawahara A, Wilm T, Solnica-Krezel L, Dawid IB (2000b) Functional interaction of vega2 and goosecoid homeobox genes in zebraﬁsh. Genesis 28: 58–67 Klein SL (1987) The ﬁrst cleavage furrow demarcates the dorsal– ventral axis in Xenopus embryos. Dev Biol 120: 299–304 Ladher R, Mohun TJ, Smith JC, Snape AM (1996) Xom: a Xenopus homeobox gene that mediates the early effects of BMP-4. Development 122: 2385–2394 Latinkic BV, Smith JC (1999) Goosecoid and mix.1 represses Brachyury expression and are required for head formation in Xenopus. Development 125: 1769–1779 Lee HX, Ambrosio AL, Reversade B, De Robertis EM (2006) Embryonic dorsal–ventral signaling: secreted frizzled-related pro- teins as inhibitors of tolloid proteinases. Cell 124: 147–159 Lewis SL, Khoo P-L, De Young RA, Bildsoe H, Wakamiya M, Behringer RR, Mukhopadhyay M, Westphal H, Tam PPL (2006) Genetic interaction of Gsc and Dkk1 in head morphogenesis of the mouse. Mech Dev 124: 157–165 Lim J, Choi K-W (2003) Bar homeodomain proteins are anti- proneural in the Drosophila eye: transcriptional repression of atonal by Bar prevents ectopic retinal neurogenesis. Development 130: 5965–5974 Melby AE, Beach C, Mullins M, Kimelman D (2000) Patterning the early zebraﬁsh by the opposing actions of bozozok and vox/vent. Dev Biol 224: 275–285 Melby AE, Clements WK, Kimelman D (1999) Regulation of dorsal gene expression in Xenopus by the ventralizing homeodomain gene Vox. Dev Biol 211: 293–305 Moretti PAB, Davidson AJ, Baker E, Lilley B, Zon LI, D’Andrea RJ (2001) Molecular cloning of a human Vent-like homeobox gene. Genomics 76: 21–29 Niehrs C (2001) The Spemann organizer and embryonic head induction. EMBO J 20: 631–637 Niehrs C, Pollet N (1999) Synexpression groups in eukaryotes. Nature 402: 483–487 Niehrs C, Keller R, Cho KWY, De Robertis EM (1993) The homeobox gene goosecoid controls cell migration in Xenopus embryos. Cell 72: 491–503 Niehrs C, Steinbeisser H, De Robertis EM (1994) Mesodermal patterning by a gradient of the vertebrate homeobox gene goose- coid. Science 263: 817–820 Oelgeschla¨ger M, Kuroda H, Reversade B, De Robertis EM (2003) Chordin is required for the Spemann organizer transplantation phenomenon in Xenopus embryos. Dev Cell 4: 219–230 Onichtchouk D, Gawantka V, Dosch R, Delius H, Hirschfeld K, Blumenstock C, Niehrs C (1996) The Xvent-2 homeobox gene is part of the BMP-4 signalling pathway controlling dorsoventral patterning of Xenopus mesoderm. Development 122: 3045–3053 Onichtchouk D, Glinka A, Niehrs C (1998) Requirement for Xvent-1 and Xvent-2 gene function in dorsoventral patterning of Xenopus mesoderm. Development 125: 1447–1456 Papalopulu N, Kintner C (1996) A Xenopus gene, Xbr-1, deﬁnes a novel class of homeobox genes and is expressed in the dorsal ciliary margin of the eye. Dev Biol 174: 104–114 & 2007 European Molecular Biology Organization Self-regulation by Gsc and Vent1/2 V Sander et al Polli M, Amaya E (2002) A study of mesoderm patterning through the analysis of the regulation of Xmyf-5 expression. Development 129: 2917–2927 Rastegar S, Friedle H, Frommer G, Knoechel W (1999) Transcriptional regulation of Xvent homeobox genes. Mech Dev 81: 139–149 Reig G, Cabrejos ME, Concha ML (2006) Functions of BarH tran- scription factors during embryonic development. Dev Biol 302: 367–375 Reversade B, De Robertis EM (2005) Regulation of ADMP and BMP2/4/7 at opposite embryonic poles generates a self-regulat- ing morphogenetic ﬁeld. Cell 123: 1147–1160 Rivera-Pe´rez JA, Mallo M, Gendron-Maguire M, Gridley T, Behringer RR (1995) Goosecoid is not an essential component of the mouse gastrula organizer but is required for craniofacial and rib development. Development 121: 3005–3012 Saito T, Sawamoto K, Okano H, Anderson DJ, Mikoshiba K (1998) Mammalian BarH homologue is a potential regulator of neural bHLH genes. Dev Biol 199: 216–225 Sasai Y, Lu B, Steinbeisser H, Geissert D, Gont LK, De Robertis EM (1994) Xenopus chordin: a novel dorsalizing factor activated by organizer-speciﬁc homeobox genes. Cell 79: 779–790 Sander V, Mullegger J, Lepperdinger G (2001) Xenopus brevican is expressed in the notochord and the brain during early embry- ogenesis. Mech Dev 102: 251–253 Schmidt JE, von Dassow G, Kimelman D (1996) Regulation of dorsal–ventral patterning: the ventralizing effects of the novel Xenopus homeobox gene Vox. Development 122: 1711–1721 Schuler-Metz A, Kno¨chel S, Kaufmann E, Kno¨chel W (2000) The homeodomain transcription factor Xvent-2 mediates autocatalytic regulation of BMP-4 expression in Xenopus embryos. J Biol Chem 275: 34365–34374 Seiliez I, Thisse B, Thisse C (2005) FoxA3 and goosecoid promote anterior neural fate through inhibtion of Wnt8a activity before the onset of gastrulation. Dev Biol 290: 152–163 Sive HL, Grainger RM, Harland RM (2000) Early Development of Xenopus laevis: A Laboratory Manual. Cold Spring Harbor, NY, USA: Cold Spring Harbor Laboratory Press Steinbeisser H, De Robertis EM, Ku M, Kessler D, Melton DA (1993) Xenopus axis formation: induction of goosecoid by injected Xwnt- 8 and activin mRNAs. Development 118: 499–507 Steinbeisser H, Fainsod A, Niehrs C, Sasai Y, De Robertis EM (1995) The role of gsc and BMP-4 in dorsal-ventral patterning of the marginal zone in Xenopus: a loss-of-function study using anti- sense RNA. EMBO J 14: 5230–5243 Struhl G (1989) Differing strategies for organizing anterior and posterior body pattern in Drosophila embryos. Nature 338: 741– 744 Tissier-Seta J-P, Mucchielli M-L, Mark M, Mattei M-G, Goridis C, Brunet J-F (1995) Barx1, a new mouse homeodomain transcrip- tion factor expressed in cranio-facial ectomesenchyme and the stomach. Mech Dev 51: 3–15 Trindade M, Tada M, Smith JC (1999) DNA-binding speciﬁcity and embryological function of Xom (Xvent-2). Dev Biol 216: 442–456 Wright CV, Morita EA, Wilkin DJ, De Robertis EM (1990) The Xenopus XlHbox 6 homeo protein, a marker of posterior neural induction, is expressed in proliferating neurons. Development 109: 225–234 Yamada G, Mansouri A, Torres M, Stuart ET, Blum M, Schultz M, De Robertis EM, Gruss P (1995) Targeted mutation of the murine goosecoid gene results in craniofacial defects and neonatal death. Development 121: 2917–2922 Yao J, Kessler DS (2001) Goosecoid promotes head organizer activity by direct repression of Xwnt8 in Spemann’s organizer. Development 128: 2975–2987 Zhu L, Belo JA, De Robertis EM, Stern CD (1999) Goosecoid regulates the neural inducing strength of the mouse node. Dev Biol 216: 276–281 The EMBO Journal is published by Nature Publishing Group on behalf of European Molecular Biology Organization. This article is licensed under a Creative Commons Attribution License <http:// creativecommons.org/licenses/by/2.5/> The EMBO Journal VOL 26 | NO 12 | 2007 2965