低氧誘發因子(hypoxia-inducible factor，HIF)為一群具有bHLH-PAS此保守區域的基因調控蛋白，最主要的功能在調節生物體內供氧的平衡(oxygen homeostasis)。在最近的研究中，發現此低氧誘發因子參與著胚胎發育的過程，當此蛋白形成異偶合體結構(heterodimer)時，具有調控下游基因的能力。細胞內缺氧時，低氧誘發因子(hypoxia-inducible factor，包括hif 1α、 hif 2α、 hif 3α)會與另一bHLH-PAS蛋白ARNT(aryl hydrocarbon receptor translocator，亦稱為hif-1β)形成安定的蛋白異偶合體結構，藉由辨識目標基因啟動子上缺氧感應序列（HRE，hypoxia response element）調控下游基因的表現，如VEGF、GLUT1、 NOS 、EPO 、LDH-A，目前已知超過40種以上的基因受到調控（Semenza, 2002）。
先前，本實驗室成功的在斑馬魚（zebrafish）胚胎選殖出兩段hif基因，包括hif 1α以及hif 3α，利用RNA全覆式原位雜交法（whole mount in situ hybridization）觀察，顯示在咽胚期兩者RNA表現重疊出現在頭部感覺器官的耳囊、 嗅基板 、中腦以及後腦、 髓腦。此外hif 1α在36∼48hpf會表現在軟骨性內顱(cartilaginous neurocranium)，而hif 3α會表現在咽弧（pharygeal arches）的部位。綜合上述我們推測hif 1α、 hif 3α對於頭部頭骨的發育扮演相當重要的角色，因此我們依據hif 1α、 hif 3α的 cDNA序列設計合成antisense反股之morpholino-integrated寡核酸（MO）(Heasman, 2002; Penberthy et al., 2002; Summerton and Weller, 1997)，將這些寡核酸利用顯微注射（microinjection）送入斑馬魚胚胎當中，此寡核酸會與hif 1α、 hif 3α之mRNA配對進而抑制蛋白質的合成，之後注入hif 1α-MO、 hif 3α-MO的胚胎以頭骨發育相關專一的標視基因檢視，如：nkx2.3、shh、col2a1、gsc、hoxb2、fkd6、sox9a等，結果證明hif 1α、hif 3α對頭部頭骨發育扮演重要的角色。

Hypoxia-inducible factor 1 (HIF-1) is a master regulator of oxygen homeostasis that controls angiogenesis, erythropoiesis, and glycolysis via transcriptional activation of target genes under hypoxic conditions. HIF-1 is a heterodimeric complex, which is composed of a HIF-1α subunit and a HIF-1β/ARNT subunit, both of which are members of the basic helix-loop-helix (bHLH)-PAS family. Under hypoxia environment, the HIF-1 binds specifically to a 5’-RCGTG-3’ hypoxia-responsive element (HRE) in the promoter or enhancer of various hypoxia inducible genes, including erythropoietin, vascular endothelial growth factor, glucose transporters, and glycolytic enzymes, as well as genes involved in iron metabolism and cell survival.
Recently, two forms of hif-a cDNA, zhif-1α and zhif-3α, were cloned from zebrafish (Danio rerio) embryo. The spatiotemporal expression pattern of zhif-1α and zhif-3α in the embryo were analyzed by whole mount RNA in situ hybridization. Strong signal of zhif-1α and zhif-3α transcripts are detected in head sensory organs, otic plate, midbrain and hindbrain during development. To investigate the function of these genes in head development, zhif1a and zhif3a-specific morpholino-integrated antisense oligonucleotides (MO) were. It shows that zhif1α- and zhif3α- specific MO have severe effects in cranial skeleton development. Defective cranial skeleton development is comfirmed by the expression pattern changes of various cranial-specific markers, including nkx2.3, shh, col2a1, gsc. It suggests that zhif1α and zhif3α and their related signal pathway play important role in head skeleton development.

英文摘要………………………………………………………….1
中文摘要…………………………………………………………3
壹 、前言…………………………………………………………4
HIF蛋白背景介紹……………………………………………..4
HIF蛋白與胚胎發育…………………………………………6
HIF蛋白與腫瘤病理發生…………………………………….7
脊椎動物頭部發育……………………………………………7
斑馬魚頭骨發育………………………………………………9
貳、材料與方法……………………………………………………13
一. 材料…………………………………………………………13
A. 實驗生物……………………………………………….13
B. 菌種、質體……………………………………………..13
C. 一般化學藥品…………………………………………..13
D. 酵素及生化試劑…………………………………………13
E. 實驗藥品與配方………………………………………….14
二. 方法…………………………………………………………16
A. 斑馬魚飼養與受精胚胎之收集………………………..16
B. 斑馬魚組織全量核糖核酸RNA抽取………………….17
C. 核酸電泳分析…………………………………………...17
D. DNA分子之萃取 (DNA extraction)…………………...18
E. DNA重組接合 (Ligation)……………………………...19
F. 質體轉型 (Transformation)……………………………19
G. 反轉錄-聚合酵素連鎖反應(RT-PCR)………………....20
H. RNA全覆式原位雜交………………………………..21
I. 顯微注射 (Microinjection)……………………………….25
J. 骨頭染色( Alcian blue )………………………………….27
參、實驗結果………………………………………………………29
一、hif 1α, hif 3α morpholino(MO) 的注射…………………29
A. 外型胚胎之觀察………………………………………..29
B. 胚胎頭部軟骨型態的觀察……………………………..29
C . 胚胎頭骨大小之比較………………………………….30
二、利用hif 1α＋hif 3α- MO對頭骨發育基因的影響……..30
A.內胚層細胞發育之標識基因的影響……………………..30
A-1.nkx2.3 ……………………………………………….30
A-2. fgf3………………………………………………….30
A-3.Shh…………………………………………………..31
A-4. foxa2……………………………………………….31
A-5.Gobbi……………………………………………….31
B. 中胚層細胞發之育標識基因…………………………32
B-1.Follistatin…………………………………………..32
B-2.col2a1………………………………………………32
B-3.Gsc…………………………………………………32
B-4.MyoD………………………………………………33
C. 後腦菱腦原節發育基因的影響………………………33
C-1. hoxa2………………………………………………33
C-2. krox20………………………………………………34
C-3. hoxb2……………………………………………….34
C-4. hoxb3……………………………………………….34
C-5. pax2.1………………………………………………35
D.調控神經塉遷移的基因之影響………………………….35
D-1. dhand﹙hand2﹚…………………………………..35
D-2. fkd6……………………………………………….36
D-3. dlx2………………………………………………36
D-4. dlx3 ………………………………………………37
E. 軟骨細胞分化基因……………………………………37
E-1.sox9a………………………………………………37
E-2.chm-1………………………………………………38
E-3.col2a1………………………………………………39
三.分別單一顯微注射 hif 1α- MO以及hif 3α- MO………39
A.外型觀察…………………………………………………40
B. 對頭骨發育相關基因的影響…………………………...40
B-1. krox20 ……………………………………………….40
B-2.dlx2 …………………………………………………40
B-3.Shh………………………………………………….41
B-4.nkx2.3……………………………………………….41
B-5.Gsc………………………………………………….41
貳、 討論…………………………………………………………42
參、 參考文獻…………………………………………………..47
肆、 附圖及照片……………………………………………….59

Akimenko, M. A., Ekker, M., Wegner, J., Lin, W. and Westerfield, M. (1994). Combinatorial expression of three zebrafish genes related to distal-less: part of a homeobox gene code for the head. J Neurosci 14, 3475-3486.
Bunn, H. F., Gu, J., Huang, L. E., Park, J. W. and Zhu, H. (1998). Erythropoietin: a model system for studying oxygen-dependent gene regulation. J Exp Biol 201 ( Pt 8), 1197-1201.
Cancedda, R., Descalzi Cancedda, F. and Castagnola, P. (1995). Chondrocyte differentiation. Int Rev Cytol 159, 265-358.
Chiang, E. F., Pai, C. I., Wyatt, M., Yan, Y. L., Postlethwait, J. and Chung, B. (2001). Two sox9 genes on duplicated zebrafish chromosomes: expression of similar transcription activators in distinct sites. Dev Biol 231, 149-163.
Charrier, J. B., Teillet, M. A., Lapointe, F. and Le Douarin, N. M. (1999). Defining subregions of Hensen''s node essential for caudalward movement, midline development and cell survival. Development 126, 4771-4783.
Clouthier, D. E., Hosoda, K., Richardson, J. A., Williams, S. C., Yanagisawa, H., Kuwaki, T., Kumada, M., Hammer, R. E. and Yanagisawa, M. (1998). Cranial and cardiac neural crest defects in endothelin-A receptor-deficient mice. Development 125, 813-824.
Clouthier, D. E., Williams, S. C., Yanagisawa, H., Wieduwilt, M., Richardson, J. A. and Yanagisawa, M. (2000). Signaling pathways crucial for craniofacial development revealed by endothelin-A receptor-deficient mice. Dev Biol 217, 10-24.
Compernolle, V., Brusselmans, K., Acker, T., Hoet, P., Tjwa, M., Beck, H., Plaisance, S., Dor, Y., Keshet, E., Lupu, F. et al. (2002). Loss of HIF-2alpha and inhibition of VEGF impair fetal lung maturation, whereas treatment with VEGF prevents fatal respiratory distress in premature mice. Nat Med 8, 702-710.
Dolle, P., Price, M. and Duboule, D. (1992). Expression of the murine Dlx-1 homeobox gene during facial, ocular and limb development. Differentiation 49, 93-99.
Emerson, C. P., Jr. (1993). Embryonic signals for skeletal myogenesis:arriving at the beginning. Curr Opin Cell Biol 5, 1057-1064.
Ellies, D. L., Langille, R. M., Martin, C. C., Akimenko, M. A. and Ekker, M. (1997). Specific craniofacial cartilage dysmorphogenesis coincides with a loss of dlx gene expression in retinoic acid-treated zebrafish embryos. Mech Dev 61, 23-36.
Ekker, M., Akimenko, M. A., Bremiller, R. and Westerfield, M. (1992). Regional expression of three homeobox transcripts in the inner ear of zebrafish embryos. Neuron 9, 27-35.
Gould, A., Itasaki, N. and Krumlauf, R. (1998). Initiation of rhombomeric Hoxb4 expression requires induction by somites and a retinoid pathway. Neuron 21, 39-51.
Greenwood, A. L., Turner, E. E. and Anderson, D. J. (1999). Identification of dividing, determined sensory neuron precursors in the mammalian neural crest. Development 126, 3545-3559.
Hayami, T., Shukunami, C., Mitsui, K., Endo, N., Tokunaga, K., Kondo, J., Takahashi, H. E. and Hiraki, Y. (1999). Specific loss of chondromodulin-I gene expression in chondrosarcoma and the suppression of tumor angiogenesis and growth by its recombinant protein in vivo. FEBS Lett 458, 436-440.
Heasman, J. (2002). Morpholino oligos: making sense of antisense? Dev Biol 243, 209-214.
Heisenberg, C. P., Tada, M., Rauch, G. J., Saude, L., Concha, M. L., Geisler, R., Stemple, D. L., Smith, J. C. and Wilson, S. W. (2000). Silberblick/Wnt11 mediates convergent extension movements during zebrafish gastrulation. Nature 405, 76-81.
Huang, L. E., Arany, Z., Livingston, D. M. and Bunn, H. F. (1996). Activation of hypoxia-inducible transcription factor depends primarily upon redox-sensitive stabilization of its alpha subunit. J Biol Chem 271, 32253-32259.
Ikeya, M., Lee, S. M., Johnson, J. E., McMahon, A. P. and Takada, S. (1997). Wnt signalling required for expansion of neural crest and CNS progenitors. Nature 389, 966-970.
Ivan, M. and Kaelin, W. G., Jr. (2001). The von Hippel-Lindau tumor suppressor protein. Curr Opin Genet Dev 11, 27-34.
Ivan, M., Kondo, K., Yang, H., Kim, W., Valiando, J., Ohh, M., Salic, A., Asara, J. M., Lane, W. S. and Kaelin, W. G., Jr. (2001). HIFalpha targeted for VHL-mediated destruction by proline hydroxylation: implications for O2 sensing. Science 292, 464-468.
Iyer, N. V., Kotch, L. E., Agani, F., Leung, S. W., Laughner, E., Wenger, R. H., Gassmann, M., Gearhart, J. D., Lawler, A. M., Yu, A. Y. et al. (1998). Cellular and developmental control of O2 homeostasis by hypoxia-inducible factor 1 alpha. Genes Dev 12, 149-162.
Jaakkola, P., Mole, D. R., Tian, Y. M., Wilson, M. I., Gielbert, J., Gaskell, S. J., Kriegsheim, A., Hebestreit, H. F., Mukherji, M., Schofield, C. J. et al. (2001). Targeting of HIF-alpha to the von Hippel-Lindau ubiquitylation complex by O2-regulated prolyl hydroxylation. Science 292, 468-472.
Jan, Y. N. and Jan, L. Y. (1993). HLH proteins, fly neurogenesis, and vertebrate myogenesis. Cell 75, 827-830.
Jewell, U. R., Kvietikova, I., Scheid, A., Bauer, C., Wenger, R. H. and Gassmann, M. (2001). Induction of HIF-1alpha in response to hypoxia is instantaneous. Faseb J 15, 1312-1314.
Kallio, P. J., Wilson, W. J., O''Brien, S., Makino, Y. and Poellinger, L. (1999). Regulation of the hypoxia-inducible transcription factor 1alpha by the ubiquitin-proteasome pathway. J Biol Chem 274, 6519-6525.
Kobayashi, H., Saito, T. and Koshino, T. (2002). Immunolocalization of carboxy-terminal type II procollagen peptide in regenerated articular cartilage of osteoarthritic knees after reduction of mechanical stress. Osteoarthritis Cartilage 10, 870-878.
Kamura, T., Sato, S., Iwai, K., Czyzyk-Krzeska, M., Conaway, R. C. and Conaway, J. W. (2000). Activation of HIF1alpha ubiquitination by a reconstituted von Hippel-Lindau (VHL) tumor suppressor complex. Proc Natl Acad Sci U S A 97, 10430-10435.
Karlstrom, R. O., Talbot, W. S. and Schier, A. F. (1999). Comparative synteny cloning of zebrafish you-too: mutations in the Hedgehog target gli2 affect ventral forebrain patterning. Genes Dev 13, 388-393.
Kimmel, C. B., Miller, C. T. and Moens, C. B. (2001). Specification and morphogenesis of the zebrafish larval head skeleton. Dev Biol 233, 239-257.
Kline, D. D., Peng, Y. J., Manalo, D. J., Semenza, G. L. and Prabhakar, N. R. (2002). Defective carotid body function and impaired ventilatory responses to chronic hypoxia in mice partially deficient for hypoxia-inducible factor 1 alpha. Proc Natl Acad Sci U S A 99, 821-826.
LaBonne, C. and Bronner-Fraser, M. (1998). Neural crest induction in Xenopus: evidence for a two-signal model. Development 125, 2403-2414.
Liem, K. F., Jr., Tremml, G., Roelink, H. and Jessell, T. M. (1995). Dorsal differentiation of neural plate cells induced by BMP-mediated signals from epidermal ectoderm. Cell 82, 969-979.
Miller, C. T., Schilling, T. F., Lee, K., Parker, J. and Kimmel, C. B. (2000). sucker encodes a zebrafish Endothelin-1 required for ventral pharyngeal arch development. Development 127, 3815-3828.
Morasso, M. I., Mahon, K. A. and Sargent, T. D. (1995). A Xenopus distal-less gene in transgenic mice: conserved regulation in distal limb epidermis and other sites of epithelial-mesenchymal interaction. Proc Natl Acad Sci U S A 92, 3968-3972.
Miller, C. T., Schilling, T. F., Lee, K., Parker, J. and Kimmel, C. B. (2000). sucker encodes a zebrafish Endothelin-1 required for ventral pharyngeal arch development. Development 127, 3815-3828.
Olson, E. N. and Klein, W. H. (1994). bHLH factors in muscle development: dead lines and commitments, what to leave in and what to leave out. Genes Dev 8, 1-8.
Olson, E. N. (1993). Regulation of muscle transcription by the MyoD family. The heart of the matter. Circ Res 72, 1-6.
Penberthy, W. T., Shafizadeh, E. and Lin, S. (2002). The zebrafish as a model for human disease. Front Biosci 7, d1439-1453.
Phillips, B. T., Bolding, K. and Riley, B. B. (2001). Zebrafish fgf3 and fgf8 encode redundant functions required for otic placode induction. Dev Biol 235,351-365.
Piotrowski, T. and Nusslein-Volhard, C. (2000). The endoderm plays an important role in patterning the segmented pharyngeal region in zebrafish (Danio rerio). Dev Biol 225, 339-356.
Piotrowski, T., Schilling, T. F., Brand, M., Jiang, Y. J., Heisenberg, C. P., Beuchle, D., Grandel, H., van Eeden, F. J., Furutani-Seiki, M., Granato, M. et al. (1996). Jaw and branchial arch mutants in zebrafish II: anterior arches and cartilage differentiation. Development 123, 345-356.
Pogoda, H. M., Solnica-Krezel, L., Driever, W. and Meyer, D. (2000). The zebrafish forkhead transcription factor FoxH1/Fast1 is a modulator of nodal signaling required for organizer formation. Curr Biol 10, 1041-1049.
Ravi, R., Mookerjee, B., Bhujwalla, Z. M., Sutter, C. H., Artemov, D., Zeng, Q., Dillehay, L. E., Madan, A., Semenza, G. L. and Bedi, A. (2000). Regulation of tumor angiogenesis by p53-induced degradation of hypoxia-inducible factor 1alpha. Genes Dev 14, 34-44.
Ryan, H. E., Lo, J. and Johnson, R. S. (1998). HIF-1 alpha is required for solid tumor formation and embryonic vascularization. Embo J 17, 3005-3015.
Robinson, G. W. and Mahon, K. A. (1994). Differential and overlapping expression domains of Dlx-2 and Dlx-3 suggest distinct roles for Distal-less homeobox genes in craniofacial development. Mech Dev 48, 199-215.
Sampath, K., Rubinstein, A. L., Cheng, A. M., Liang, J. O., Fekany, K., Solnica-Krezel, L., Korzh, V., Halpern, M. E. and Wright, C. V. (1998). Induction of the zebrafish ventral brain and floorplate requires cyclops/nodal signalling. Nature 395, 185-189.
Sachdev, S. W., Dietz, U. H., Oshima, Y., Lang, M. R., Knapik, E. W., Hiraki,Y. and Shukunami, C. (2001). Sequence analysis of zebrafish chondromodulin-1 and expression profile in the notochord and chondrogenic regions during cartilage morphogenesis. Mech Dev 105, 157-162.
Schauerte, H. E., van Eeden, F. J., Fricke, C., Odenthal, J., Strahle, U. and Haffter, P. (1998). Sonic hedgehog is not required for the induction of medial floor plate cells in the zebrafish. Development 125, 2983-2993.
Schier, A. F. and Shen, M. M. (2000). Nodal signalling in vertebrate development. Nature 403, 385-389.
Schilling, T. F., Walker, C. and Kimmel, C. B. (1996). The chinless mutation and neural crest cell interactions in zebrafish jaw development. Development 122, 1417-1426.
Sela-Donenfeld, D. and Kalcheim, C. (1999). Regulation of the onset of neural crest migration by coordinated activity of BMP4 and Noggin in the dorsal neural tube. Development 126, 4749-4762.
Semenza, G. L. (1999). Regulation of mammalian O2 homeostasis by hypoxia-inducible factor 1. Annu Rev Cell Dev Biol 15, 551-578.
Semenza, G. L. (2001). Hypoxia-inducible factor 1: control of oxygen homeostasis in health and disease. Pediatr Res 49, 614-617.
Semenza, G. L. (2001). Hypoxia-inducible factor 1: oxygen homeostasis and disease pathophysiology. Trends Mol Med 7, 345-350.
Schneider-Maunoury, S., Seitanidou, T., Charnay, P. and Lumsden, A. (1997). Segmental and neuronal architecture of the hindbrain of Krox-20 mouse mutants. Development 124, 1215-1226.
Schneider-Maunoury, S., Seitanidou, T., Topilko, P., Vesque, C., Frain, M., Gilardi-Hebenstreit, P. and Charnay, P. (1997). [Role of the Krox-20 gene in development of rhombencephalon]. C R Seances Soc Biol Fil 191, 91-94.
Srivastava, D., Cserjesi, P. and Olson, E. N. (1995). A subclass of bHLH proteins required for cardiac morphogenesis. Science 270, 1995-1999.
Shukunami, C., Iyama, K., Inoue, H. and Hiraki, Y. (1999). Spatiotemporal pattern of the mouse chondromodulin-I gene expression and its regulatory role in vascular invasion into cartilage during endochondral bone formation. Int J Dev Biol 43, 39-49.
Sladek, F. M., Zhong, W. M., Lai, E. and Darnell, J. E., Jr. (1990). Liver-enriched transcription factor HNF-4 is a novel member of the steroid hormone receptor superfamily. Genes Dev 4, 2353-2365.
Shukunami, C., Yamamoto, S., Tanabe, T. and Hiraki, Y. (1999). Generation of multiple transcripts from the chicken chondromodulin-I gene and their expression during embryonic development. FEBS Lett 456, 165-170.
Sirotkin, H. I., Gates, M. A., Kelly, P. D., Schier, A. F. and Talbot, W. S. (2000). Fast1 is required for the development of dorsal axial structures in zebrafish. Curr Biol 10, 1051-1054.
Stachel, S. E., Grunwald, D. J. and Myers, P. Z. (1993). Lithium perturbation and goosecoid expression identify a dorsal specification pathway in the pregastrula zebrafish. Development 117, 1261-1274.
Summerton, J. and Weller, D. (1997). Morpholino antisense oligomers: design, preparation, and properties. Antisense Nucleic Acid Drug Dev 7, 187-195.
Summerton, J., Stein, D., Huang, S. B., Matthews, P., Weller, D. and Partridge, M. (1997). Morpholino and phosphorothioate antisense oligomers compared in cell-free and in-cell systems. Antisense Nucleic Acid Drug Dev 7, 63-70.
Trainor, P. A. and Krumlauf, R. (2001). Hox genes, neural crest cells and branchial arch patterning. Curr Opin Cell Biol 13, 698-705.
Thomas, T., Kurihara, H., Yamagishi, H., Kurihara, Y., Yazaki, Y., Olson, E. N. and Srivastava, D. (1998). A signaling cascade involving endothelin-1, dHAND and msx1 regulates development of neural-crest-derived branchial arch mesenchyme. Development 125, 3005-3014.
Wang, G. L., Jiang, B. H., Rue, E. A. and Semenza, G. L. (1995). Hypoxia-inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension. Proc Natl Acad Sci U S A 92, 5510-5514.
Wenger, R. H. (2002). Cellular adaptation to hypoxia: O2-sensing protein hydroxylases, hypoxia-inducible transcription factors, and O2-regulated gene expression. Faseb J 16, 1151-1162.
Weintraub, H. (1993). The MyoD family and myogenesis: redundancy, networks,and thresholds. Cell 75, 1241-1244.
Weigel, D., Jurgens, G., Kuttner, F., Seifert, E. and Jackle, H. (1989). The homeotic gene fork head encodes a nuclear protein and is expressed in the terminal regions of the Drosophila embryo. Cell 57, 645-658.
Wilkinson, D. G., Bhatt, S., Cook, M., Boncinelli, E. and Krumlauf, R. (1989). Segmental expression of Hox-2 homoeobox-containing genes in the developing mouse hindbrain. Nature 341, 405-409.
Xu, D., Emoto, N., Giaid, A., Slaughter, C., Kaw, S., deWit, D. and Yanagisawa, M. (1994). ECE-1: a membrane-bound metalloprotease that catalyzes the proteolytic activation of big endothelin-1. Cell 78, 473-485.
Yu, A. Y., Shimoda, L. A., Iyer, N. V., Huso, D. L., Sun, X., McWilliams, R., Beaty, T., Sham, J. S., Wiener, C. M., Sylvester, J. T. et al. (1999). Impaired physiological responses to chronic hypoxia in mice partially deficient for hypoxia-inducible factor 1alpha. J Clin Invest 103, 691-696.
Zhang, Q. J., Zhan, H., Li, T., Hao, A. G., Wan, C. H. and Xin, Y. M. (1999). [Effects of simulated flight hypobaric hypoxia and oxygen inhalation on free radical metabolism in various organs of mice]. Space Med Med Eng (Beijing) 12, 414-417.
Zhong, H., De Marzo, A. M., Laughner, E., Lim, M., Hilton, D. A., Zagzag, D., Buechler, P., Isaacs, W. B., Semenza, G. L. and Simons, J. W. (1999). Overexpression of hypoxia-inducible factor 1alpha in common human cancers and their metastases. Cancer Res 59, 5830-5835.
Zhang, X. M., Lin, E. and Yang, X. J. (2000). Sonic hedgehog-mediated ventralization disrupts formation of the midbrain-hindbrain junction in the chick embryo. Dev Neurosci 22, 207-216.
Zhao, G. Q., Zhao, S., Zhou, X., Eberspaecher, H., Solursh, M. and de Crombrugghe, B. (1994). rDlx, a novel distal-less-like homeoprotein is expressed in developing cartilages and discrete neuronal tissues. Dev Biol 164, 37-51.