NUCLEOTIDE AND PROTEIN SEQUENCES OF VERTEBRATE DELTA GENES AND METHODS BASED THEREON

Abstract: The present invention relates to nucleotide sequences of vertebrate Delta genes, and amino acid sequences of their encoded proteins, as well as derivatives (e.g., fragments) and analogs thereof. In a specific embodiment, the vertebrate Delta protein is a human protein. The invention further relates to fragments (and derivatives and analogs thereof) of Delta which comprise one or more domains of the Delta protein, including but not limited to the intracellular domain, extracellular domain, DSL domain, domain amino-terminal to the DSL domain, transmembrane region, or one or more EGF-like repeats of a Delta protein, or any combination of the foregoing. Antobidies to Delta, its derivatives and analogs, are additionally provided. Methods of production of the Delta proteins, derivatives and analogs, e.g., by recombinant means, are also provided. Therapeutic and diagnostic methods and pharmaceutical compositions are provided. In specific examples, isolated Delta genes, from Xenopus, chick, mouse, and human, are provided.

Description: NUCLEOTIDE AND PROTEIN SEQUENCES OF VERTEBRATE DELTA GENES AND METHODS BASED THEREON This application claims priority to United States Provisional Application Serial No. 60/000,589 filed June 28, 1995, which is incorporated by reference herein in its entirety. 1. INTRODUCTION The present invention relates to vertebrate Delta genes and their encoded protein products, as well as derivatives and analogs thereof. Production of vertebrate Delta proteins, derivatives, and antibodies is also provided. The invention further relates to therapeutic compositions and methods of diagnosis and therapy. 2. BACKGROUND OF THE INVENTION Genetic analyses in Drosophila have been extremely useful in dissecting the complexity of developmental pathways and identifying interacting loci. However, understanding the precise nature of the processes that underlie genetic interactions requires a knowledge of the protein products of the genes in question. The vertebrate central nervous system is an intimate mixture of different cell types, almost all generated from the same source - the neurogenic epithelium that forms the neural plate and subsequently the neural tube. What are the mechanisms that control neurogenesis in this sheet of cells, directing some to become neurons while others remain non-neuronal? The answer is virtually unknown for vertebrates, but many of the cellular interactions and genes controlling cell fate decisions during neurogenesis have been well characterized in Drosophila (Campos-Ortega, 1993, J. Neurobiol. 24:1305-1327) . Although the gross anatomical context of neurogenesis appears very different in insects and vertebrates, the possibility remains that, at a cellular level, similar events are occurring via conserved molecular mechanisms. Embryological, genetic and molecular evidence indicates that the early steps of ectodermal differentiation in Drosophila depend on cell interactions (Doe and Goodman, 1985, Dev. Biol. 111:206-219; Technau and Campos-Ortega, 5 1986, Dev. Biol. 195:445-454; Vassin et al., 1985, J. Neurogenet. 2:291-308; de la Concha et al., 1988, Genetics 118:499-508; Xu et al. , 1990, Genes Dev. 4:464-475; Artavanis-Tsakonas, 1988, Trends Genet. 4:95-100). Mutational analyses reveal a small group of zygotically- 10 acting genes, the so called neurogenic loci, which affect the choice of ectodermal cells between epidermal and neural pathways (Poulson, 1937, Proc. Natl. Acad. Sci. 23:133-137; Leh ann et al., 1983, Wilhelm Roux's Arch. Dev. Biol. 192:62- 74; Jϋrgens et al., 1984, Wilhelm Roux's Arch. Dev. Biol. 15 193:283-295; Wieschaus et al., 1984, Wilhelm Roux's Arch. Dev. Biol. 193:296-307; Nϋsslein-Volhard et al., 1984, Wilhelm Roux's Arch. Dev. Biol. 193:267-282). Null mutations in any one of the zygotic neurogenic loci — Notch (N) , Delta (Dl) , mastermind (mam) , Enhancer of Split (E(spl ) , neuralized 20 (neu) , and big brain (bib) — result in hypertrophy of the nervous system at the expense of ventral and lateral epidermal structures. This effect is due to the misrouting of epidermal precursor cells into a neuronal pathway, and implies that neurogenic gene function is necessary to divert 25 cells within the neurogenic region from a neuronal fate to an epithelial fate. Neural precursors arise in the Drosophila embryo from a neurogenic epithelium during successive waves of neurogenesis (Campos-Ortega & Hartenstein, 1985, The 30 embryonic development of Drosophila melanogaster (Springer-Verlag, Berlin; New York); Doe, 1992, Development 116:855-863). The pattern of production of these cells is largely determined by the activity of the proneural and neurogenic genes. Proneural genes predispose clusters of 35 cells to a neural fate (reviewed in Skeath & Carroll, 1994, Faseb J. 8:714-21), but only a subset of cells in a cluster become neural precursors. This restriction is due to the action of the neurogenic genes, which mediate lateral inhibition - a type of inhibitory cell signaling by which a cell committed to a neural fate forces its neighbors either to remain uncommitted or to enter a non-neural pathway 5 (Artavanis-Tsakonas & Simpson, 1991, Trends Genet. 7:403-408; Doe & Goodman, 1985, Dev. Biol. 111:206-219). Mutations leading to a failure of lateral inhibition cause an overproduction of neurons - the "neurogenic" phenotype (Lehmann et al., 1981, Roux's Arch. Dev. Biol. 190:226-229; 10 Lehmann et al., Roux's Arch. Dev. Biol. 192:62-74). In Droεophila , the inhibitory signal is delivered by a transmembrane protein encoded by the Delta neurogenic gene, which is displayed by the nascent neural cells (Heitzler & Simpson, 1991, Cell 64:1083-1092) . Neighboring cells express 15 a transmembrane receptor protein, encoded by the neurogenic gene Notch (Fortini & Artavanis-Tsakonas, 1993, Cell 75:1245-1247). Delta has been identified as a genetic unit capable of interacting with the Notch locus (Xu et al. , 1990, Genes Dev. 4:464-475). 20 Mutational analyses also reveal that the action of the neurogenic genes is pleiotropic and is not limited solely to embryogenesis. For example, ommatidial, bristle and wing formation, which are known also to depend upon cell interactions, are affected by neurogenic mutations (Morgan et 25 al., 1925, Bibliogr. Genet. 2:1-226; Welshons, 1956, Dros. Inf. Serv. 30:157-158; Preiss et al., 1988, EMBO J. 7:3917- 3927; Shellenbarger and Mohler, 1978, Dev. Biol. 62:432-446; Technau and Campos-Ortega, 1986, Wilhelm Roux's Dev. Biol. 195:445-454; Tomlison and Ready, 1987, Dev. Biol. 120:366- 30 376; Cagan and Ready, 1989, Genes Dev. 3:1099-1112). Neurogenic genes are also required for normal development of the muscles, gut, excretory and reproductive systems of the fly (Muskavitch, 1994, Dev. Biol. 166:415-430). Both Notch and Delta are transmembrane proteins 35 that span the membrane a single time (Wharton et al., 1985, Cell 43:567-581; Kidd and Young, 1986, Mol. Cell. Biol. 6:3094-3108; Vassin, et al., 1987, EMBO J. 6:3431-3440; Kopczynski, et al., 1988, Genes Dev. 2:1723-1735) and include multiple tandem EGF-like repeats in their extracellular domains (Muskavitch, 1994, Dev. Biol. 166:415-430). The Notch gene encodes a -300 kd protein (we use "Notch" to 5 denote this protein) with a large N-terminal extracellular domain that includes 36 epidermal growth factor (EGF) -like tandem repeats followed by three other cysteine-rich repeats, designated Notch/lin-12 repeats (Wharton, et al., 1985, Cell 43:567-581; Kidd and Young, 1986, Mol. Cell. Biol. 6:3094- 10 3108; Yochem, et al., 1988, Nature 335:547-550). Molecular studies have lead to the suggestion that Notch and Delta constitute biochemically interacting elements of a cell communication mechanism involved in early developmental decisions (Fehon et al., 1990, Cell 61:523-534). Homologs 15 are found in Caenorhabditis elegans , where the Notch-related gene lin-12 and the Delta-related gene lag-2 are also responsible for lateral inhibition (Sternberg, 1993, Current Biol. 3:763-765; Henderson et al. , 1994, Development 120:2913-2924; Greenwald, 1994, Curr. Opin. Genet. Dev. 20 4:556-562). In vertebrates, several Notch homologs have also been identified (Kopan & Weintraub, 1993, J. Cell Biol. 121:631-641; Lardelli et al., 1994, Mech. Dev. 46:123-136; Lardelli & Lendahl, 1993, Exp. Cell Res. 204:364-372; Weinmaster et al., 1991, Development 113:199-205; Weinmaster 25 et al., 1992, Development 116:931-941; Coffman et al. , 1990, Science 249:1438-1441; Bierkamp & Campos-Ortega, 1993, Mech. Dev. 43:87-100), and they are expressed in many tissues and at many stages of development. Loss of Notch-1 leads to somite defects and embryonic death in mice (Swiatek et al. , 30 1994, Genes Dev. 8:707-719; Conlon et al., Rossant, J. Development (J. Dev. 121:1533-1545), while constitutively active mutant forms of Notch-1 appear to inhibit cell differentiation in Xenopus and in cultured mammalian cells (Coffman et al., 1993, Cell 73:659-671; Kopan et al., 1994, 35 Development 120:2385-2396; Nye et al. , 1994, Development 120:2421-2430) . The EGF-like motif has been found in a variety of proteins, including those involved in the blood clotting cascade (Furie and Furie, 1988, Cell 53: 505-518) . In particular, this motif has been found in extracellular proteins such as the blood clotting factors IX and X (Rees et al., 1988, EMBO J. 7:2053-2061; Furie and Furie, 1988, Cell 53: 505-518), in other Droεophila genes (Knust et al., 1987 EMBO J. 761-766; Rothberg et al., 1988, Cell 55:1047-1059), and in some cell-surface receptor proteins, such as thrombomodulin (Suzuki et al., 1987, EMBO J. 6:1891-1897) and LDL receptor (Sudhof et al., 1985, Science 228:815-822). A protein binding site has been mapped to the EGF repeat domain in thrombomodulin and urokinase (Kurosawa et al., 1988, J. Biol. Chem 263:5993-5996; Appella et al. , 1987, J. Biol. Chem. 262:4437-4440). Citation of references hereinabove shall not be construed as an admission that such references are prior art to the present invention. 3. SUMMARY OF THE INVENTION The present invention relates to nucleotide sequences of vertebrate Delta genes (chick and mouse Delta , and related genes of other species) , and amino acid sequences of their encoded proteins, as well as derivatives (e . g. , fragments) and analogs thereof. Nucleic acids hybridizable to or complementary to the foregoing nucleotide sequences are also provided. In a specific embodiment, the Delta protein is a mammalian protein, preferably a human protein. The invention relates to vertebrate Delta derivatives and analogs of the invention which are functionally active, i.e., they are capable of displaying one or more known functional activities associated with a full- length (wild-type) Delta protein. Such functional activities include but are not limited to antigenicity [ability to bind (or compete with Delta for binding) to an anti-Delta antibody] , immunogenicity (ability to generate antibody which binds to Delta) , ability to bind (or compete with Delta for binding) to Notch or other toporythmic proteins or fragments thereof ("adhesiveness"), ability to bind (or compete with Delta for binding) to a receptor for Delta. "Toporythmic proteins" as used herein, refers to the protein products of Notch , Delta , Serrate , Enhancer of split , and Deltex, as well as other members of this interacting set of genes which may be identified, e . g . , by virtue of the ability of their gene sequences to hybridize, or their homology to Delta, Serrate, or Notch, or the ability of their genes to display phenotypic interactions or the ability of their protein products to interact biochemically. The invention further relates to fragments (and derivatives and analogs thereof) of a vertebrate Delta that comprise one or more domains of the Delta protein, including but not limited to the intracellular domain, extracellular domain, transmembrane domain, DSL domain, domain amino¬ terminal to the DSL domain, or one or more EGF-like (homologous) repeats of a Delta protein, or any combination of the foregoing. Antibodies to a vertebrate Delta, its derivatives and analogs, are additionally provided. Methods of production of the vertebrate Delta proteins, derivatives and analogs, e.g., by recombinant means, are also provided. The present invention also relates to therapeutic and diagnostic methods and compositions based on Delta proteins and nucleic acids. The invention provides for treatment of disorders of cell fate or differentiation by administration of a therapeutic compound of the invention. Such therapeutic compounds (termed herein "Therapeutics") include: Delta proteins and analogs and derivatives (including fragments) thereof; antibodies thereto; nucleic acids encoding the Delta proteins, analogs, or derivatives; and Delta antisense nucleic acids. In a preferred embodiment, a Therapeutic of the invention is administered to treat a cancerous condition, or to prevent progression from a pre-neoplastic or non-malignant state into a neoplastic or a malignant state. In other specific embodiments, a Therapeutic of the invention is administered to treat a nervous system disorder or to promote tissue regeneration and repair. In one embodiment, Therapeutics which antagonize, or inhibit, Notch and/or Delta function (hereinafter "Antagonist Therapeutics") are administered for therapeutic effect. In another embodiment, Therapeutics which promote Notch and/or Delta function (hereinafter "Agonist Therapeutics") are administered for therapeutic effect. Disorders of cell fate, in particular hyperproliferative (e.g., cancer) or hypoproliferative disorders, involving aberrant or undesirable levels of expression or activity or localization of Notch and/or Delta protein can be diagnosed by detecting such levels, as described more fully infra . In a preferred aspect, a Therapeutic of the invention is a protein consisting of at least a fragment (termed herein "adhesive fragment") of Delta which mediates binding to a Notch protein or a fragment thereof. 3.1. DEFINITIONS As used herein, underscoring or italicizing the name of a gene shall indicate the gene, in contrast to its encoded protein product which is indicated by the name of the gene in the absence of any underscoring. For example, "Delta" shall mean the Delta gene, whereas "Delta" shall indicate the protein product of the Delta gene. 4. DESCRIPTION OF THE FIGURES Figure 1A-1B. IA. The DNA sequence of chick Delta (C-Delta-1 ) (SEQ ID NO:l). IB. The DNA sequence of an alternatively spliced chick Delta (C-Delta-1) (SEQ ID N0:3). Figure 2. The predicted amino acid sequence of chick Delta (C-Delta-1) (SEQ ID NO:2). Figure 3. Predicted amino acid sequence of C-Delta-1 (SEQ ID NO:2), aligned with that of X-Delta-1 (Xenopus Delta; SEQ ID NO:5) and Drosophila Delta (SEQ ID NO:6) and, indicating the conserved domain structures: EGF repeats, DSL domain, and transmembrane domain (TM) . Conserved amino acids are boxed, and • denote aligned and non-aligned N-terminal cysteine residues, respectively. Although the intracellular domains of C-Delta-1 and X-Delta-1 closely resemble each other, they show no significant homology to the corresponding part of Drosophila Delta. Figure 4. Alignment of DSL domains from C-Delta-1 (SEQ ID N0:2), Droεophila Delta (SEQ ID NO:6) (Vassin et al., 1987, EMBO J. 6:3431-3440; Kopczynski et al., 1988, Genes Dev. 2:1723-1735), Droεophila Serrate (SEQ ID NO:7) (Fleming et al., 1990, Genes Dev. 4:2188-2201; Thomas et al., 1991, Development 111:749-761), C-Serrate-1 (SEQ ID NO:8) (Myat, Henrique, Ish-Horowicz and Lewis, in preparation), Apx-1 (SEQ ID NO:9) (Mello et al., 1994, Cell 77:95-106) and Lag-2 (SEQ ID NO:10) (Henderson et al., 1994, Development 120:2913-2924; Tax et al., 1994, Nature 368:150-154), showing the conserved Cysteine spacings, the amino acids that are conserved between presumed ligands for Notch-like proteins in Droεophila and vertebrates, and those that are further conserved in C. eleganε ligands (boxes) . Figure 5A-5E. C-Delta-1 and C-Notch-1 expression correlate with onset of neurogenesis in the one-day (El) neural plate. Anterior is to the left. Wholemount in situ hybridization specimens are shown in Figure 5a-d; 5e is a section. Figure 5a, At stage 7, C-Notch-1 is expressed throughout most of the neural plate and part of the underlying preso itic mesoderm. Figure 5b , C-Delta-1 at stage 7 is already detectable in the neural plate, in the future posterior hindbrain, just anterior to the firεt somite (white box) . The posterior end of this neural domain is roughly level with the anterior margin of a domain of very strong expression in the underlying presomitic mesoderm (psm) . Earlier expression in the neural plate may occur and be masked by expression in the underlying mesoderm (unpublished results) . Figure 5c, Higher magnification view of the area boxed in 5b , showing scattered cells in the neural plate expressing C-Delta-1 . Figure 5d, At stage 8, C-Delta-1 expression in the neural plate extends posteriorly as the neural plate develops. The domain of labelled neural plate cells visible in this photograph (bracketed) continues posteriorly over the presomitic mesoderm. Figure 5e, Parasagittal section of a stage 8 embryo showing that C-Delta-1 is expressed in scattered cells of the neural plate (dorsal layer of tissue; bracketed) , and broadly in the presomitic mesoderm (ventral layer) . The plane of section is slightly oblique, missing the posterior part of the neural plate domain (cf. 5d) . Figure 6A-6C. C-Delta-2-expressing cells do not incorporate BrdU. Of 612 C-Delta-1 " cells, 581 were BrdU " (76 sectionε; 6 embryos) . Figure 6a, Diagram showing how phase in the cell cycle is related to apico-basal poεition of the nucleuε for cells in the neuroepithelium; S-phase nuclei lie basally (Fujita, 1963, J. Comp. Neurol. 120:37-42; Biffo et al., 1992, Histoche . Cytochem. 40:535-540). Nuclei are indicated by shading. Figure 6b , Section through the neural tube of a stage 9 embryo labelled for 2 h with BrdU showing C-Delta-1 expresεing cellε (dark on blue background) and BrdU-labelled nuclei (pink) . Labelled nuclei are predominantly baεal, where DNA εyntheεis occurs, yet basal C-Del t a-l -expr ss ing cells are unlabelled. Figure 6c, Section through a stage 9 embryo incubated for 4h: many labelled nuclei have exited S-phase and have moved towards the lumen, but C-Delta-1-expreεεing cells are still basal and not labelled with BrdU. Figure 7. The DNA sequence of mouse Delta (K-Delta-1) (SEQ ID NO: 11) . Figure 8. The predicted amino acid sequence of the mouse Delta (M-Delta-1) (SEQ ID N0:12) . Figure 9. An alignment of the predicted amino acid sequence of mouεe M-Delta-1 (SEQ ID NO: 12) with the chick C- Delta-1 (SEQ ID NO:2) which εhowε their extenεive amino acid εequence identity. Identical amino acidε are boxed. The consensus sequence between the two genes is at the bottom (SEQ ID NO:13) . Figure 10. The DNA sequence of a PCR amplified fragment of human Delta (E-Delta-1 ) (SEQ ID NO: 14) and the predicted amino acid sequenceε uεing the three available open reading frames, 2nd line (SEQ ID NO:15), 3rd line (SEQ ID NO:16), 4th line (SEQ ID NO: 17) . Figure 11. An alignment of human H-Delta-1 (top line) and chick C-Delta-1 (bottom line) . The predicted amino acid sequence of human Delta (SEQ ID NO:18) is shown in the top line. The sequence of human Delta was determined by "eye", in which the sequence of the appropriate reading frame was determined by maximizing homology with C-Delta-1. No single reading frame shown in Figure 10 gave the correct sequence due to errors in the DNA sequence of Figure 10 that caused reading frameshiftε. Figure 12A-12B. Figure 12A presents the contig DNA sequence of human Delta (H-Delta-1) (SEQ ID NO:33) from clone HDI 18. Figure 12B presents the nucleotide sequence εhown in Figure 12A (top line, SEQ ID NO:33) and the deduced amino acid sequences using the three possible open reading frames, second line (SEQ ID NO:34), third line (SEQ ID NO:35), fourth line (SEQ ID NO:36). The amino acid sequence with the greatest homology to the mouse Delta-l amino acid εequence is boxed. This boxed amino acid sequence is the predicted amino acid εequence of human Delta; where the reading frame shifts indicates where a sequencing error is present in the sequence. No εingle reading frame shown in Figure 12A gave an uninterrupted amino acid sequence due to errors in the DNA sequence that caused shiftε in the reading frame. X indicateε an undetermined amino acid; N indicateε an undetermined nucleotide. Figure 13. An alignment of mouse M-Delta-1 DNA sequence (top line, SEQ ID NO:37) and human H-Delta-1 DNA sequence (second line, SEQ ID NO:33) and their consenεuε εequence (third line, SEQ ID NO:38). Figure 14. The composite human Delta (H-Delta-1) amino acid sequence (SEQ ID NOS: 39-65, respectively) is presented, representing the boxed amino sequence from Figure 12B. ">" indicates that the sequence continues on the line below. "*" indicates a break in the sequence. 5. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to nucleotide sequenceε of vertebrate Delta geneε, and amino acid εequences of their encoded proteins. The invention further relates to fragments and other derivatives, and analogs, of vertebrate Delta proteins. Nucleic acids encoding such fragments or derivatives are also within the scope of the invention. The invention provides Delta geneε and their encoded proteinε of many different vertebrate εpecies. The Delta geneε of the invention include chick, mouεe, and human Delta and related geneε (homologε) in other vertebrate εpecieε. In εpecific embodiments, the Delta genes and proteins are from vertebrates, or more particularly, mammals. In a preferred embodiment of the invention, the Delta protein is a human protein. Production of the foregoing proteins and derivatives, e.g., by recombinant methods, is provided. The invention relateε to Delta derivativeε and analogs of the invention which are functionally active, i.e., they are capable of displaying one or more known functional activities aεεociated with a full-length (wild-type) Delta protein. Such functional activitieε include but are not limited to antigenicity [ability to bind (or compete with Delta for binding) to an anti-Delta antibody] , immunogenicity (ability to generate antibody which bindε to Delta) , ability to bind (or compete with Delta for binding) to Notch or other toporythmic proteins or fragments thereof ("adhesiveneεε") , ability to bind (or compete with Delta for binding) to a receptor for Delta, ability to affect cell fate differentiation, and therapeutic activity. "Toporythmic proteinε" as used herein, referε to the protein productε of Notch , Delta , Serrate , Enhancer of split , and Deltex, as well as other members of this interacting gene family which may be identified, e.g., by virtue of the ability of their gene sequenceε to hybridize, or their homology to Delta, Serrate, or Notch, or the ability of their genes to display phenotypic interactions. The invention further relates to fragmentε (and derivativeε and analogε thereof) of Delta which compriεe one or more domains of the Delta protein, including but not limited to the intracellular domain, extracellular domain, DSL domain, region amino-terminal to the DSL domain, transmembrane domain, membrane-associated region, or one or more EGF-like (homologous) repeats of a Delta protein, or any combination of the foregoing. Antibodies to vertebrate Delta, its derivatives and analogs, are additionally provided. Aε demonεtrated infra , Delta playε a critical role in development and other phyεiological procesεeε, in particular, aε a ligand to Notch, which iε involved in cell fate (differentiation) determination. In particular, Delta iε believed to play a major role in determining cell fates in the central nervous system. The nucleic acid and amino acid sequenceε and antibodies thereto of the invention can be used for the detection and quantitation of Delta mRNA and protein of human and other species, to study expresεion thereof, to produce Delta and fragmentε and other derivativeε and analogs thereof, in the study and manipulation of differentiation and other physiological processeε. The preεent invention alεo relateε to therapeutic and diagnoεtic methods and compositions based on Delta proteins and nucleic acids. The invention provides for treatment of disorders of cell fate or differentiation by administration of a therapeutic compound of the invention. Such therapeutic compounds (termed herein "Therapeutics") include: Delta proteins and analogs and derivatives (including fragments) thereof; antibodieε thereto; nucleic acidε encoding the Delta proteinε, analogε, or derivativeε; and Delta antisense nucleic acids. In a preferred embodiment, a Therapeutic of the invention is adminiεtered to treat a cancerous condition, or to prevent progreεεion from a pre-neoplaεtic or non-malignant state into a neoplastic or a malignant state. In other specific embodimentε, a Therapeutic of the invention is administered to treat a nervous system disorder or to promote tissue regeneration and repair. In one embodiment, Therapeutics which antagonize, or inhibit, Notch and/or Delta function (hereinafter "Antagonist Therapeutics") are administered for therapeutic effect. In another embodiment, Therapeutics which promote Notch and/or Delta function (hereinafter "Agonist Therapeutics") are administered for therapeutic effect. Diεorderε of cell fate, in particular hyperproliferative (e.g., cancer) or hypoproliferative diεorderε, involving aberrant or undeεirable levelε of expreεεion or activity or localization of Notch and/or Delta protein can be diagnoεed by detecting such levels, aε described more fully infra . In a preferred aspect, a Therapeutic of the invention is a protein conεiεting of at leaεt a fragment (termed herein "adheεive fragment") of Delta which mediateε binding to a Notch protein or a fragment thereof. The invention iε illustrated by way of examples infra which diεcloεe, inter alia , the cloning of a chick Delta homolog (Section 6) , the cloning of a mouεe Delta homolog (Section 7) , and the cloning of a human Delta homolog (Section 8) . For clarity of diεcloεure, and not by way of limitation, the detailed deεcription of the invention is divided into the subεectionε which follow. 5.1. ISOLATION OF THE DELTA GENES The invention relateε to the nucleotide εequenceε of vertebrate Delta nucleic acids. In specific embodimentε, human Delta nucleic acidε compriεe the cDNA sequences shown in Figure 10 (SEQ ID NO: 14) or in Figure 12A (SEQ ID NO:33), or the coding regions thereof, or nucleic acidε encoding a vertebrate Delta protein (e.g., having the εequence of SEQ ID NO:l, 3, 11, 14 or 33) . The invention provideε nucleic acidε conεisting of at least 8 nucleotides (i.e., a hybridizable portion) of a vertebrate Delta 5 sequence; in other embodiments, the nucleic acids consiεt of at leaεt 25 (continuous) nucleotides, 50 nucleotides, 100 nucleotides, 150 nucleotides, or 200 nucleotides of a Delta sequence, or a full-length Delta coding sequence. The invention also relates to nucleic acids hybridizable to or 10 complementary to the foregoing sequences or their complements. In specific aspects, nucleic acids are provided which comprise a sequence complementary to at least 10, 25, 50, 100, or 200 nucleotides or the entire coding region of a vertebrate Delta gene. In a specific embodiment, a nucleic 15 acid which is hybridizable to a vertebrate (e.g., mammalian) Delta nucleic acid (e.g., having sequence SEQ ID N0:14 or SEQ ID NO:33, or an at leaεt 10, 25, 50, 100, or 200 nucleotide portion thereof) , or to a nucleic acid encoding a Delta derivative, under conditionε of low stringency is provided. 20 By way of example and not limitation, procedures uεing εuch conditions of low stringency are as follows (see also Shilo and Weinberg, 1981, Proc. Natl. Acad. Sci. USA 78:6789-6792): Filterε containing DNA are pretreated for 6 h at 40°C in a solution containing 35% formamide, 5X SSC, 50 mM Tris-HCl 25 (pH 7.5), 5 mM EDTA, 0.1% PVP, 0.1% Ficoll, 1% BSA, and 500 μg/ml denatured salmon sperm DNA. Hybridizations are carried out in the same solution with the following modifications: 0.02% PVP, 0.02% Ficoll, 0.2% BSA, 100 μg/ml salmon sperm DNA, 10% (wt/vol) dextran sulfate, and 5-20 X 10 6 cpm 30 32 P-labeled probe is uεed. Filterε are incubated in hybridization mixture for 18-20 h at 40°C, and then waεhed for 1.5 h at 55°C in a εolution containing 2X SSC, 25 mM Triε-HCl (pH 7.4), 5 mM EDTA, and 0.1% SDS. The waεh εolution iε replaced with freεh solution and incubated an 35 additional 1.5 h at 60°C. Filters are blotted dry and exposed for autoradiography. If necessary, filters are washed for a third time at 65-68°C and reexposed to film. Other conditions of low stringency which may be used are well known in the art (e.g., as employed for cross-species hybridizations) . In another specific embodiment, a nucleic acid which is hybridizable to a vertebrate (e.g., mammalian) Delta nucleic acid under conditions of high stringency is provided. By way of example and not limitation, procedures using such conditions of high stringency are as follows: Prehybridization of filters containing DNA is carried out for 8 h to overnight at 65°C in buffer composed of 6X SSC, 50 mM Tris-HCl (pH 7.5), 1 mM EDTA, 0.02% PVP, 0.02% Ficoll, 0.02% BSA, and 500 μg/ml denatured salmon sperm DNA. Filters are hybridized for 48 h at 65°C in prehybridization mixture containing 100 μg/ml denatured εalmon εperm DNA and 5-20 X 10 δ cpm of 32 P-labeled probe. Waεhing of filters is done at 37°C for 1 h in a solution containing 2X SSC, 0.01% PVP, 0.01% Ficoll, and 0.01% BSA. This is followed by a wash in 0.1X SSC at 50°C for 45 min before autoradiography. Other conditions of high stringency which may be used are well known in the art. Nucleic acids encoding fragments and derivatives of vertebrate Delta proteins (see Section 5.6), and Delta antisenεe nucleic acidε (see Section 5.11) are additionally provided. As is readily apparent, aε uεed herein, a "nucleic acid encoding a fragment or portion of a Delta protein" εhall be conεtrued aε referring tc a nucleic acid encoding only the recited fragment or portion of the Delta protein and not the other contiguouε portionε of the Delta protein aε a continuouε εequence. Fragments of vertebrate Delta nucleic acids comprising regions of homology to other toporythmic proteins are also provided. The DSL regions (regions of homology with Drosophila Serrate and Delta) of Delta proteins of other specieε are alεo provided. Nucleic acids encoding conserved regions between Delta and Serrate, such as those shown in Figures 3 and 8 are also provided. Specific embodiments for the cloning of a vertebrate Delta gene, presented as a particular example but not by way of limitation, follows: For expression cloning (a technique commonly known in the art) , an expresεion library is constructed by methodε known in the art. For example, mRNA (e.g., human) iε iεolated, cDNA is made and ligated into an expression vector (e.g., a bacteriophage derivative) such that it is capable of being expressed by the host cell into which it is then introduced. Variouε screening asεayε can then be uεed to select for the expresεed Delta product. In one embodiment, anti-Delta antibodieε can be uεed for εelection. In another preferred aεpect, PCR iε used to amplify the deεired εequence in a genomic or cDNA library, prior to selection. Oligonucleotide primers representing known Delta sequenceε (preferably vertebrate εequenceε) can be uεed as primers in PCR. In a preferred aεpect, the oligonucleotide primerε represent at least part of the Delta conserved segments of strong homology between Serrate and Delta. The synthetic oligonucleotides may be utilized as primers to amplify by PCR εequenceε from a εource (RNA or DNA) , preferably a cDNA library, of potential intereεt. PCR can be carried out, e.g., by uεe of a Perkin-Elmer Cetuε thermal cycler and Taq polymeraεe (Gene Amp " ) . The DNA being amplified can include mRNA or cDNA or genomic DNA from any eukaryotic εpecieε. One can chooεe to εyntheεize εeveral different degenerate primerε, for use in the PCR reactions. It iε alεo possible to vary the stringency of hybridization conditionε uεed in priming the PCR reactionε, to allow for greater or leεεer degreeε of nucleotide εequence εimilarity between the known Delta nucleotide εequence and the nucleic acid homolog being iεolated. For cross species hybridization, low stringency conditions are preferred. For same εpecieε hybridization, moderately εtringent conditionε are preferred. After successful amplification of a segment of a Delta homolog, that εegment may be molecularly cloned and sequenced, and utilized as a probe to isolate a complete cDNA or genomic clone. Thiε, in turn, will permit the determination of the gene's complete nucleotide sequence, the analysis of its expression, and the production of its protein product for functional analysis, as described infra . In this fashion, additional genes encoding Delta proteins may be identified. Such a procedure is presented by way of example in various examples sections infra . The above-methods are not meant to limit the following general description of methods by which cloneε of Del ta may be obtained. Any vertebrate cell potentially can εerve aε the nucleic acid source for the molecular cloning of the Delta gene. The nucleic acid sequenceε encoding Delta can be isolated from mammalian, human, porcine, bovine, feline, avian, equine, canine, as well as additional primate sourceε, etc. For example, we have amplified fragments of the Delta gene in mouse, chicken, and human, by PCR using cDNA libraries with Delta primers. The DNA may be obtained by standard procedures known in the art from cloned DNA (e.g., a DNA "library") , by chemical syntheεiε, by cDNA cloning, or by the cloning of genomic DNA, or fragmentε thereof, purified from the desired cell. (See, for example, Sambrook et al. , 1989, Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory Presε, Cold Spring Harbor, New York; Glover, D.M. (ed.), 1985, DNA Cloning: A Practical Approach, MRL Press, Ltd., Oxford, U.K. Vol. I, II.) Clones derived from genomic DNA may contain regulatory and intron DNA regions in addition to coding regions; clones derived from cDNA will contain only exon sequenceε. Whatever the source, the gene should be molecularly cloned into a εuitable vector for propagation of the gene. In the molecular cloning of the gene from genomic DNA, DNA fragmentε are generated, some of which will encode the desired gene. The DNA may be cleaved at specific sites uεing variouε reεtriction enzymes. Alternatively, one may use DNAse in the presence of manganese to fragment the DNA, or the DNA can be physically sheared, as for example, by sonication. The linear DNA fragments can then be separated according to εize by εtandard techniques, including but not limited to, agarose and polyacrylamide gel electrophoresis and column chromatography. Once the DNA fragments are generated, identification of the specific DNA fragment containing the deεired gene may be accompliεhed in a number of ways. For example, if an amount of a portion of a Delta (of any specieε) gene or itε specific RNA, or a fragment thereof, e.g., an extracellular domain (εee Section 5.6), is available and can be purified and labeled, the generated DNA fragments may be screened by nucleic acid hybridization to the labeled probe (Benton, W. and Davis, R. , 1977, Science 196:180; Grunstein, M. And Hogness, D. , 1975, Proc. Natl. Acad. Sci. U.S.A. 72:3961). Those DNA fragments with substantial homology to the probe will hybridize. It is also posεible to identify the appropriate fragment by reεtriction enzyme digestion(ε) and comparison of fragment sizes with those expected according to a known restriction map if such is available. Further selection can be carried out on the basis of the properties of the gene. Alternatively, the presence of the gene may be detected by assays based on the physical, chemical, or immunological properties of its expreεεed product. For example, cDNA cloneε, or DNA cloneε which hybrid-select the proper mRNAs, can be selected which produce a protein that, e.g., has similar or identical electrophoretic migration, isolectric focuεing behavior, proteolytic digestion maps, binding activity, in vitro aggregation activity ("adheεiveneεs") or antigenic properties as known for Delta. If an antibody to Delta is available, the Delta protein may be identified by binding of labeled antibody to the putatively Delta synthesizing clones, in an ELISA (enzyme-linked immunosorbent assay) -type procedure. The Delta gene can also be identified by mRNA εelection by nucleic acid hybridization followed by in vitro tranεlation. In this procedure, fragments are used to iεolate complementary mRNAs by hybridization. Such DNA fragments may repreεent available, purified Del ta DNA of another εpecies (e.g., Drosophila) . Immunoprecipitation analyεis or functional assays (e.g., aggregation ability in vitro ; binding to receptor; see infra) of the in vitro translation products of the isolated products of the isolated mRNAs identifies the mRNA and, therefore, the complementary DNA fragments that contain the desired sequences. In addition, specific mRNAs may be selected by adsorption of polyεomeε isolated from cellε to immobilized antibodieε εpecifically directed againεt Delta protein. A radiolabelled Delta cDNA can be εyntheεized using the selected mRNA (from the adsorbed polysomes) as a template. The radiolabelled mRNA or cDNA may then be used as a probe to identify the Delta DNA fragments from among other genomic DNA fragmentε. Alternativeε to iεolating the Delta genomic DNA include, but are not limited to, chemically εyntheεizing the gene εequence itεelf from a known sequence or making cDNA to the mRNA which encodes the Delta protein. For example, RNA for cDNA cloning of the Delta gene can be iεolated from cellε which expreεε Delta . Other methods are posεible and within the scope of the invention. The identified and iεolated gene can then be inserted into an appropriate cloning vector. A large number of vector-host εyεtemε known in the art may be uεed. Poεsible vectors include, but are not limited to, plaεmidε or modified viruεeε, but the vector εyεtem muεt be compatible with the hoεt cell uεed. Such vectorε include, but are not limited to, bacteriophages such aε lambda derivativeε, or plasmids such as PBR322 or pUC plasmid derivatives. The insertion into a cloning vector can, for example, be accomplished by ligating the DNA fragment into a cloning vector which has complementary coheεive termini. However, if the complementary reεtriction εites used to fragment the DNA are not preεent in the cloning vector, the endε of the DNA oleculeε may be enzymatically modified. Alternatively, any εite deεired may be produced by ligating nucleotide εequenceε (linkers) onto the DNA termini; these ligated linkers may comprise specific chemically synthesized oligonucleotides encoding restriction endonuclease recognition sequences. In an alternative method, the cleaved vector and Delta gene may be modified by homopolymeric tailing. Recombinant moleculeε can be introduced into hoεt cells via transformation, tranεfection, infection, electroporation, etc. , εo that many copies of the gene sequence are generated. In an alternative method, the desired gene may be identified and isolated after insertion into a suitable cloning vector in a "shot gun" approach. Enrichment for the desired gene, for example, by size fractionation, can be done before insertion into the cloning vector. In specific embodiments, transformation of host cells with recombinant DNA molecules that incorporate the isolated Delta gene, cDNA, or syntheεized DNA sequence enables generation of multiple copies of the gene. Thus, the gene may be obtained in large quantities by growing transformants, isolating the recombinant DNA moleculeε from the tranεfor antε and, when necessary, retrieving the inserted gene from the iεolated recombinant DNA. The Delta εequenceε provided by the inεtant invention include thoεe nucleotide εequenceε encoding substantially the same amino acid sequenceε as found in native vertebrate Delta proteins, and those encoded amino acid seguenceε with functionally equivalent amino acidε, all aε described in Section 5.6 infra for Delta derivatives. 5.2. EXPRESSION OF THE DELTA GENES The nucleotide sequence coding for a vertebrate Delta protein or a functionally active fragment or other derivative thereof (see Section 5.6), can be inserted into an appropriate expression vector, i.e., a vector which contains the necesεary elements for the transcription and translation of the inserted protein-coding sequence. The necesεary tranεcriptional and tranεlational signalε can alεo be supplied by the native Delta gene and/or its flanking regionε. A variety of hoεt-vector εyεtemε may be utilized to express the protein-coding sequence. These include but are not limited to mammalian cell systems infected with virus (e.g., vaccinia virus, adenovirus, etc.) ; insect cell systems infected with virus (e.g., baculovirus) ; microorganiεmε εuch as yeast containing yeast vectors, or bacteria transformed with bacteriophage, DNA, plasmid DNA, or cosmid DNA. The expression elements of vectors vary in their strengths and specificities. Depending on the host-vector system utilized, any one of a number of suitable transcription and translation elements may be used. In a specific embodiment, the adhesive portion of the Delta gene is expresεed. In other εpecific embodiments, the human Delta gene iε expreεεed, or a εequence encoding a functionally active portion of human Delta. In yet another embodiment, a fragment of Delta compriεing the extracellular domain, or other derivative, or analog of Delta iε expreεεed. Any of the methods previously deεcribed for the insertion of DNA fragmentε into a vector may be uεed to conεtruct expreεεion vectorε containing a chimeric gene conεiεting of appropriate tranεcriptional/tranεlational control εignals and the protein coding sequenceε. Theεe methodε may include in vitro recombinant DNA and εynthetic techniqueε and in vivo recombinantε (genetic recombination) . Expreεεion of nucleic acid εequence encoding a Delta protein or peptide fragment may be regulated by a εecond nucleic acid εequence εo that the Delta protein or peptide is expresεed in a host transformed with the recombinant DNA molecule. For example, expresεion of a Delta protein may be controlled by any promoter/enhancer element known in the art. Promoters which may be used to control Delta gene expreεsion include, but are not limited to, the SV40 early promoter region (Bernoist and Chambon, 1981, Nature 290:304-310), the promoter contained in the 3' long terminal repeat of Rous sarcoma virus (Yamamoto, et al., 1980, Cell 22:787-797), the herpes thymidine kinase promoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445), the regulatory sequences of the metallothionein gene (Brinster et al., 1982, Nature 296:39-42); prokaryotic expression vectors such as the 3-lactamase promoter (Villa-Kamaroff, et al., 1978, Proc. Natl. Acad. Sci. U.S.A. 75:3727-3731), or the tac promoter (DeBoer, et al., 1983, Proc. Natl. Acad. Sci. U.S.A. 80:21- 5 25) ; εee alεo "Useful proteins from recombinant bacteria" in Scientific American, 1980, 242:74-94; plant expresεion vectorε compriεing the nopaline εynthetase promoter region (Herrera-Estrella et al. , Nature 303:209-213) or the cauliflower mosaic virus 35S RNA promoter (Gardner, et al., 10 1981, Nucl. Acids Reε. 9:2871), and the promoter of the photoεynthetic enzyme ribulose biphosphate carboxylaεe (Herrera-Estrella et al., 1984, Nature 310:115-120); promoter elements from yeast or other fungi such as the Gal 4 promoter, the ADC (alcohol dehydrogenase) promoter, PGK 15 (phosphoglycerol kinase) promoter, alkaline phosphatase promoter, and the following animal transcriptional control regions, which exhibit tissue specificity and have been utilized in transgenic animals: elaεtase I gene control region which is active in pancreatic acinar cells (Swift et 20 al., 1984, Cell 38:639-646; Ornitz et al., 1986, Cold Spring Harbor Symp. Quant. Biol. 50:399-409; MacDonald, 1987, Hepatology 7:425-515); insulin gene control region which iε active in pancreatic beta cellε (Hanahan, 1985, Nature 315:115-122), immunoglobulin gene control region which iε 25 active in lymphoid cellε (Groεεchedl et al., 1984, Cell 38:647-658; Adameε et al., 1985, Nature 318:533-538; Alexander et al. , 1987, Mol. Cell. Biol. 7:1436-1444), mouεe mammary tumor viruε control region which iε active in testicular, breast, lymphoid and maεt cellε (Leder et al., 30 1986, Cell 45:485-495), albumin gene control region which iε active in liver (Pinkert et al., 1987, Genes and Devel. 1:268-276), alpha-fetoprotein gene control region which is active in liver (Krumlauf et al., 1985, Mol. Cell. Biol. 5:1639-1648; Hammer et al., 1987, Science 235:53-58; alpha 1- 35 antitrypsin gene control region which is active in the liver (Kelsey et al. , 1987, Genes and Devel. 1:161-171), beta- globin gene control region which is active in myeloid cellε (Mogram et al. , 1985, Nature 315:338-340; Kollias et al., 1986, Cell 46:89-94; myelin basic protein gene control region which is active in oligodendrocyte cells in the brain (Readhead et al. , 1987, Cell 48:703-712); myosin light chain- 2 gene control region which is active in skeletal muεcle (Sani, 1985, Nature 314:283-286), and gonadotropic releasing hormone gene control region which is active in the hypothalamuε (Maεon et al., 1986, Science 234:1372-1378). Expression vectors containing Delta gene insertε can be identified by three general approacheε: (a) nucleic acid hybridization, (b) preεence or abεence of "marker" gene functions, and (c) expresεion of inserted sequenceε. In the first approach, the presence of a foreign gene inserted in an expresεion vector can be detected by nucleic acid hybridization uεing probeε compriεing sequences that are homologous to an inserted toporythmic gene. In the second approach, the recombinant vector/hoεt εyεtem can be identified and selected based upon the presence or absence of certain "marker" gene functions (e.g., thymidine kinase activity, resistance to antibiotics, transformation phenotype, occlusion body formation in baculoviruε, etc.) caused by the insertion of foreign genes in the vector. For example, if the Delta gene is inserted within the marker gene sequence of the vector, recombinants containing the Delta insert can be identified by the absence of the marker gene function.. In the third approach, recombinant expresεion vectorε can be identified by aεεaying the foreign gene product expreεεed by the recombinant. Such aεεayε can be baεed, for example, on the phyεical or functional propertieε of the Delta gene product in vitro aεsay systems, e . g . , aggregation (binding) with Notch, binding to a receptor, binding with antibody. Once a particular recombinant DNA molecule is identified and isolated, several methodε known in the art may be used to propagate it. Once a suitable host system and growth conditionε are eεtabliεhed, recombinant expreεεion vectorε can be propagated and prepared in quantity. Aε previouεly explained, the expression vectors which can be used include, but are not limited to, the following vectors or their derivatives: human or animal viruses such as vaccinia virus or adenovirus; insect viruses such as baculovirus; yeast vectors; bacteriophage vectors (e.g., lambda) , and plasmid and cosmid DNA vectorε, to name but a few. In addition, a host cell strain may be choεen which modulateε the expression of the inserted sequenceε, or modifies and processeε the gene product in the εpecific fashion deεired. Expreεεion from certain promoterε can be elevated in the preεence of certain inducerε; thuε, expression of the genetically engineered Delta protein may be controlled. Furthermore, different host cells have characteristic and εpecific mechaniεmε for the tranεlational and poεt-translational processing and modification (e.g., glycosylation, cleavage [e.g., of signal sequence]) of proteins. Appropriate cell lines or host systemε can be chosen to ensure the desired modification and processing of the foreign protein expressed. For example, expression in a bacterial syεtem can be used to produce an unglycosylated core protein product. Expression in yeaεt will produce a glycosylated product. Expresεion in mammalian cellε can be uεed to ensure "native" glycosylation of a heterologous mammalian Delta protein. Furthermore, different vector/host expresεion systemε may effect proceεsing reactions such as proteolytic cleavageε to different extents. In other specific embodiments, the Delta protein, fragment, analog, or derivative may be expressed as a fusion, or chimeric protein product (comprising the protein, fragment, analog, or derivative joined via a peptide bond to a heterologouε protein εequence (of a different protein)). Such a chimeric product can be made by ligating the appropriate nucleic acid εequenceε encoding the deεired amino acid sequences to each other by methods known in the art, in the proper coding frame, and expressing the chimeric product by methods commonly known in the art. Alternatively, such a chimeric product may be made by protein εynthetic techniques, e.g., by use of a peptide synthesizer. Both cDNA and genomic sequences can be cloned and expressed. 5.3. IDENTIFICATION AND PURIFICATION OF THE DELTA GENE PRODUCTS In particular aspects, the invention provides amino acid sequenceε of a vertebrate Delta, preferably a human Delta, and fragments and derivatives thereof which comprise an antigenic determinant (i.e., can be recognized by an antibody) or which are otherwiεe functionally active, aε well aε nucleic acid sequenceε encoding the foregoing. "Functionally active" material aε uεed herein referε to that material diεplaying one or more known functional activitieε aεεociated with a full-length (wild-type) Delta protein, e.g., binding to Notch or a portion thereof, binding to any other Delta ligand, antigenicity (binding to an anti-Delta antibody) , etc. In specific embodiments, the invention provideε fragmentε of a Delta protein conεiεting of at leaεt 6 amino acidε, 10 amino acidε, 25 amino acids, 50 amino acids, or of at least 75 amino acids. Moleculeε compriεing εuch fragments are also provided. In other embodiments, the proteins comprise or consist esεentially of an extracellular domain, DSL domain, epidermal growth factor-like repeat (ELR) domain, one or any combination of ELRε, transmembrane domain, or intracellular (cytoplasmic) domain, or a portion which bindε to Notch, or any combination of the foregoing, of a vertebrate Delta protein. Fragmentε, or proteinε compriεing fragmentε, lacking some or all of the foregoing regions of a Delta protein are alεo provided. Nucleic acids encoding the foregoing are provided. Once a recombinant which expresses the Delta gene sequence is identified, the gene product can be analyzed. This is achieved by asεays based on the physical or functional properties of the product, including radioactive labelling of the product followed by analysis by gel electrophoresis, immunoassay, etc. Once the Delta protein is identified, it may be isolated and purified by standard methods including chromatography (e.g., ion exchange, affinity, and sizing column chromatography) , centrifugation. differential solubility, or by any other standard technique for the purification of proteins. The functional properties may be evaluated using any suitable asεay (εee Section 5.7) . Alternatively, once a Delta protein produced by a recombinant is identified, the amino acid sequence of the protein can be deduced from the nucleotide sequence of the chimeric gene contained in the recombinant. As a result, the protein can be synthesized by standard chemical methods known in the art (e.g., εee Hunkapiller, M. , et al., 1984, Nature 310:105-111) . In a εpecific embodiment of the preεent invention, such Delta proteinε, whether produced by recombinant DNA techniqueε or by chemical εynthetic methodε, include but are not limited to thoεe containing, as a primary amino acid sequence, all or part of the amino acid sequenceε εubεtantially aε depicted in Figureε 2, 8, 11 or 14 (SEQ ID NOS:2, 10, 16 and 39-65), aε well aε fragmentε and other derivativeε, and analogs thereof. 5.4. STRUCTURE OF THE DELTA GENES AND PROTEINS The structure of the vertebrate Delta genes and proteins can be analyzed by variouε methodε known in the art. 5.4.1. GENETIC ANALYSIS The cloned DNA or cDNA correεponding to the Delta gene can be analyzed by methodε including but not limited to Southern hybridization (Southern, E.M. , 1975, J. Mol. Biol. 98:503-517), Northern hybridization (εee e.g., Freeman et al., 1983, Proc. Natl. Acad. Sci. U.S.A. 80:4094-4098), restriction endonuclease mapping (Maniatis, T. , 1982, Molecular Cloning, A Laboratory, Cold Spring Harbor, New York) , and DNA sequence analysis. Polymerase chain reaction (PCR; U.S. Patent Nos. 4,683,202, 4,683,195 and 4,889,818; Gyllenεtein et al., 1988, Proc. Natl. Acad. Sci. U.S.A. 85:7652-7656; Ochman et al., 1988, Geneticε 120:621-623; Loh et al., 1989, Science 243:217-220) followed by Southern hybridization with a Delta-specific probe can allow the detection of the Delta gene in DNA from various cell types. Methodε of amplification other than PCR are commonly known and can alεo be employed. In one embodiment, Southern hybridization can be uεed to determine the genetic linkage of Delta . Northern hybridization analysiε can be uεed to determine the expreεεion of the Delta gene. Variouε cell typeε, at varicuε εtates of development or activity can be tested for Delta expresεion. Exampleε of such techniques and their reεultε are deεcribed in Section 6, infra . The εtringency of the hybridization conditionε for both Southern and Northern hybridization can be manipulated to ensure detection of nucleic acidε with the deεired degree of relatedneεε to the εpecific Delta probe uεed. Reεtriction endonucleaεe mapping can be uεed to roughly determine the genetic εtructure of the Delta gene. Restriction maps derived by restriction endonuclease cleavage can be confirmed by DNA sequence analysiε. DNA εequence analyεiε can be performed by any techniqueε known in the art, including but not limited to the method of Maxam and Gilbert (1980, Meth. Enzymol. 65:499- 560), the Sanger dideoxy method (Sanger, F., et al. , 1977, Proc. Natl. Acad. Sci. U.S.A. 74:5463) , the uεe of T7 DNA polymeraεe (Tabor and Richardεon, U.S. Patent No. 4,795,699), or uεe of an automated DNA εequenator (e.g., Applied Bioεystems, Foster City, CA) . 5.4.2. PROTEIN ANALYSIS The amino acid sequence of the Delta protein can be derived by deduction from the DNA sequence, or alternatively, by direct sequencing of the protein, e.g., with an automated amino acid sequencer. The amino acid sequence of a representative Delta protein compriseε the εequence εubstantially as depicted in Figure 2 , and detailed in Section 6, infra , with the representative mature protein that shown by amino acid numbers 1-728. The Delta protein sequence can be further characterized by a hydrophilicity analysiε (Hopp, T. and Woodε, K., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:3824). A hydrophilicity profile can be used to identify the hydrophobic and hydrophilic regions of the Delta protein and the corresponding regions of the gene sequence which encode such regionε. Hydrophilic regions are more likely to be immunogenic. Secondary, structural analysiε (Chou, P. and Faε an, G. , 1974, Biochemiεtry 13:222) can alεo be done, to identify regionε of Delta that assume specific secondary structureε. Manipulation, tranεiation, and secondary εtructure prediction, as well aε open reading frame prediction and plotting, can alεo be accompliεhed using computer εoftware programε available in the art. Other methodε of εtructural analyεiε can also be employed. These include but are not limited to X-ray crystallography (Engεtom, A., 1974, Biochem. Exp. Biol. 11:7- 13) and computer modeling (Fletterick, R. and Zoller, M. (edε.), 1986, Computer Graphics and Molecular Modeling, in Current Communications in Molecular Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York) . 5.5. GENERATION OF ANTIBODIES TO DELTA PROTEINS AND DERIVATIVES THEREOF ——— — According to the invention, a vertebrate Delta protein, its fragments or other derivatives, or analogs thereof, may be used as an immunogen to generate antibodies which recognize such an immunogen. Such antibodies include but are not limited to polyclonal, monoclonal, chimeric, single chain, Fab fragments, and an Fab expreεεion library. In a εpecific embodiment, antibodieε to human Delta are produced. In another embodiment, antibodies to the extracellular domain of Delta are produced. In another embodiment, antibodies to the intracellular domain of Delta are produced. Various procedures known in the art may be used for the production of polyclonal antibodies to a Delta protein or derivative or analog. In a particular embodiment, rabbit polyclonal antibodies to an epitope of the Delta protein encoded by a sequence depicted in Figures la, lb, 7 or 11, or a subεequence thereof, can be obtained. For the production of antibody, various host animals can be immunized by injection with the native Delta protein, or a synthetic versi.on, or derivative (e.g., fragment) thereof, including but not limited to rabbitε, mice, rats, etc. Various adjuvantε may be uεed to increaεe the immunological response, depending on the hoεt εpecieε, and including but not limited to Freund's (complete and incomplete) , mineral gels such as aluminum hydroxide, surface active εubεtanceε such as lysolecithin, pluronic polyols, polyanionε, peptideε, oil emulεions, keyhole limpet hemocyaninε, dinitrophenol, and potentially useful human adjuvants εuch aε BCG (bacille Calmette-Guerin) and corynebacterium parvum. For preparation of monoclonal antibodieε directed toward a Delta protein sequence or analog thereof, any technique which provides for the production of antibody molecules by continuous cell lines in culture may be used. For example, the hybridoma technique originally developed by Kohler and Milstein (1975, Nature 256:495-497), as well as the trioma technique, the human B-cell hybridoma technique (Kozbor et al., 1983, Immunology Today 4:72), and the EBV- hybridoma technique to produce human monoclonal antibodies (Cole et al., 1985, in Monoclonal Antibodies and Cancer Therapy, Alan R. Lisε, Inc., pp. 77-96). In an additional embodiment of the invention, monoclonal antibodies can be produced in germ-free animals utilizing recent technology (PCT/US90/02545) . According to the invention, human antibodies may be used and can be obtained by uεing human hybridomas (Cote et al. , 1983, Proc. Natl. Acad. Sci. U.S.A. 80:2026-2030) or by transforming human B cells with EBV virus in vitro (Cole et al., 1985, in Monoclonal Antibodies and Cancer Therapy, Alan R. Lisε, pp. 77-96) . In fact, according to the invention, techniques developed for the production of "chimeric antibodies" (Morriεon et al., 1984, Proc. Natl. Acad. Sci. U.S.A. 81:6851-6855; Neuberger et al. , 1984, Nature 312:604-608; Takeda et al., 1985, Nature 314:452-454) by splicing the genes from a mouse antibody molecule specific for Delta together with genes from a human antibody molecule of appropriate biological activity can be used; such antibodieε are within the εcope of thiε invention. According to the invention, techniqueε deεcribed for the production of εingle chain antibodies (U.S. Patent 4,946,778) can be adapted to produce Delta-specific single chain antibodies. An additional embodiment of the invention utilizes the techniques deεcribed for the conεtruction of Fab expreεεion librarieε (Huεe et al . , 1989, Science 246:1275- 1281) to allow rapid and eaεy identification of monoclonal Fab fragmentε with the deεired εpecificity for Delta proteinε, derivatives, or analogs. Antibody fragments which contain the idiotype of the molecule can be generated by known techniques. For example, εuch fragments include but are not limited to: the F(ab') 2 fragment which can be produced by pepsin digestion of the antibody molecule; the Fab' fragments which can be generated by reducing the disulfide bridges of the F(ab') 2 fragment, and the Fab fragmentε which can be generated by treating the antibody molecule with papain and a reducing agent. In the production of antibodieε, screening for the desired antibody can be accomplished by techniques known in the art, e.g. ELISA (enzyme-linked immunosorbent assay). For example, to select antibodies which recognize a εpecific domain of a vertebrate Delta protein, one may aεεay generated hybridomaε for a product which bindε to a Delta fragment containing εuch domain. For εelection of an antibody immunoεpecific to human Delta, one can select on the basis of positive binding to human Delta and a lack of binding to Drosophila Delta. The foregoing antibodies can be used in methods known in the art relating to the localization and activity of the protein sequences of the invention (e.g., see Section 5.7, infra) , e . g . , for imaging theεe proteins, measuring levels thereof in appropriate physiological samples, in diagnostic methods, etc. Antibodieε specific to a domain of a Delta protein are also provided. In a specific embodiment, antibodies which bind to a Notch-binding fragment of Delta are provided. In another embodiment of the invention (see infra) , anti-Delta antibodies and fragments thereof containing the binding domain are Therapeutics. 5.6. DELTA PROTEINS. DERIVATIVES AND ANALOGS The invention further relates to vertebrate (e.g., mammalian) Delta proteins, a d derivatives (including but not limited tc fragments) and analogs of vertebrate Delta proteins. Nucleic acids encoding Delta protein derivatives and protein analogs are also provided. In one embodiment, the Delta proteins are encoded by the Delta nucleic acids described in Section 5.1 supra . In particular aspects, the proteins, derivatives, or analogε are of mouse, chicken, rat, pig, cow, dog, monkey, or human Delta proteins. In a εpecific embodiment, a mature, full-length vertebrate Delta protein iε provided. In one embodiment, a vertebrate Delta protein lacking only the signal sequence (approximately the first 17 amino-terminal amino acidε) is provided. The production and uεe of derivativeε and analogε related to Delta are within the εcope of the preεent invention. In a εpecific embodiment, the derivative or analog iε functionally active, i.e., capable of exhibiting one or more functional activities asεociated with a full- length, wild-type Delta protein. Aε one example, εuch derivativeε or analogε which have the deεired immunogenicity or antigenicity can be uεed, for example, in immunoaεεayε, for immunization, for inhibition of Delta activity, etc. Such molecules which retain, or alternatively inhibit, a desired Delta property, e.g., binding to Notch or other toporythmic proteins, binding to a cell-εurface receptor, can be uεed aε inducers, or inhibitors, respectively, of such property and its physiological correlates. A specific embodiment relates to a Delta fragment that can be bound by an anti-Delta antibody but cannot bind to a Notch protein or other toporythmic protein. Derivatives or analogs of Delta can be tested for the desired activity by procedures known in the art, including but not limited to the asεays described in Section 5.7. In particular, Delta derivatives can be made by altering Delta sequences by subεtitutionε, additionε or deletionε that provide for functionally equivalent moleculeε. Due to the degeneracy of nucleotide coding εequenceε, other DNA εequenceε which encode substantially the same amino acid sequence aε a Delta gene may be uεed in the practice of the preεent invention. Theεe include but are not limited to nucleotide εequenceε compriεing all or portionε of Delta geneε which are altered by the εubstitution of different ccdons that encode a functionally equivalent amino acid residue within the sequence, thus producing a εilent change. Likewiεe, the Delta derivativeε of the invention include, but are not limited to, thoεe containing, as a primary amino acid sequence, all or part of the amino acid sequence of a Delta protein including altered εequenceε in which functionally equivalent amino acid reεidueε are εubstituted for residues within the sequence resulting in a εilent change. For example, one or more amino acid residueε within the εequence can be εubεtituted by another amino acid of a εimilar polarity which actε aε a functional equivalent, resulting in a silent alteration. Subεtituteε for an amino acid within the εequence may be εelected from other memberε of the class to which the amino acid belongs. For example, the nonpolar (hydrophobic) amino acids include alanine, leucine, iεoleucine, valine, proline, phenylalanine, tryptophan and methionine. The polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, and glutamine. The positively charged (basic) amino acids include arginine, lysine and histidine. The negatively charged (acidic) amino acids include aspartic acid and glutamic acid. In a specific embodiment of the invention, proteins consiεting of or compriεing a fragment of a vertebrate Delta protein conεisting of at least 10 (continuous) amino acids of the Delta protein iε provided. In other embodimentε, the fragment conεiεtε of at leaεt 20 or 50 amino acidε of the Delta protein. In εpecific embodimentε, εuch fragmentε are not larger than 35, 100 or 200 amino acids. Derivatives or analogs of Delta include but are not limited to those peptides which are substantially homologous to a vertebrate Delta protein or fragments thereof (e.g., at leaεt 30%, 50%, 70%, or 90% identity over an amino acid εequence of identical size — e.g., comprising a domain) or whose encoding nucleic acid iε capable of hybridizing to a coding Del ta εequence. The Delta derivativeε and analogε of the invention can be produced by variouε methodε known in the art. The manipulations which result in their production can occur at the gene or protein level. For example, the cloned Delta gene sequence can be modified by any of numerous strategieε known in the art (Maniatis, T. , 1990, Molecular Cloning, A Laboratory Manual, 2d ed. , Cold Spring Harbor Laboratory, Cold Spring Harbor, New York) . The εequence can be cleaved at appropriate εiteε with reεtriction endonuclease(s) , followed by further enzymatic modification if desired, isolated, and ligated in vitro . In the production of the gene encoding a derivative or analog of Delta, care should be taken to ensure that the modified gene remains within the same translational reading frame as Delta, uninterrupted by translational stop signals, in the gene region where the desired Delta activity iε encoded. Additionally, the Delta-encoding nucleic acid sequence can be mutated in vitro or in vivo , to create and/or destroy translation, initiation, and/or termination εequenceε, or to create variations in coding regions and/or form new restriction endonuclease sites or destroy preexisting ones, to facilitate further in vitro modification. Any technique for mutagenesiε known in the art can be uεed, including but not limited to, in vitro εite- directed mutageneεiε (Hutchinεon, C, et al., 1978, J. Biol. Chem 253:6551), uεe of TAB ® linkerε (Pharmacia), etc. PCR primerε containing εequence changeε can be uεed in PCR to introduce εuch changeε into the amplified fragmentε. Manipulations of the Delta sequence may also be made at the protein level. Included within the scope of the invention are Delta protein fragments or other derivativeε or analogs which are differentially modified during or after translation, e.g., by glycoεylation, acetylation, phoεphorylation, amidation, derivatization by known protecting/blocking groupε, proteolytic cleavage, linkage to an antibody molecule or other cellular ligand, etc. Any of numerous chemical modifications may be carried out by known techniques, including but not limited to specific chemical cleavage by cyanogen bromide, trypsin, chymotrypsin, papain, V8 protease, NaBH 4 ; acetylation, formylation, oxidation, reduction; metabolic syntheεiε in the presence of tunicamycin; etc. In addition, analogs and derivativeε of Delta can be chemically εyntheεized. For example, a peptide corresponding to a portion of a Delta protein which comprises the deεired domain (εee Section 5.6.1), or which mediateε the desired aggregation activity in vitro , or binding to a receptor, can be syntheεized by uεe of a peptide εyntheεizer. Furthermore, if deεired, nonclaεεical amino acids or chemical amino acid analogs can be introduced as a substitution or addition into the Delta sequence. Non-clasεical amino acidε include but are not limited to the D-iεomerε of the common amino acidε, α-amino isobutyric acid, 4-aminobutyric acid, hydroxyproline, εarcoεine, citrulline, cyεteic acid, t- butylglycine, t-butylalanine, phenylglycine, cyclohexylalanine, β-alanine, deεigner amino acidε such aε β- ethyl amino acidε, Cα-methyl amino acids, and Nα-methyl amino acids. In a specific embodiment, the Delta derivative iε a chimeric, or fuεion, protein compriεing a vertebrate Delta protein or fragment thereof (preferably conεiεting of at leaεt a domain or motif of the Delta protein, or at leaεt 10 amino acidε of the Delta protein) joined at itε amino- or carboxy-terminuε via a peptide bond to an amino acid εequence of a different protein. In one embodiment, εuch a chimeric protein is produced by recombinant expresεion of a nucleic acid encoding the protein (compriεing a Delta-coding εequence joined in-frame to a coding εequence for a different protein) . Such a chimeric product can be made by ligating the appropriate nucleic acid εequenceε encoding the desired amino acid sequences to each other by methods known in the art, in the proper coding frame, and expreεεing the chimeric product by methods commonly known in the art. Alternatively, such a chimeric product may be made by protein εynthetic techniqueε, e.g., by uεe ot a peptide εyntheεizer. In a specific embodiment, a chimeric nucleic acid encoding a mature Delta protein with a heterologous signal sequence is expreεεed εuch that the chimeric protein iε expreεsed and processed by the cell to the mature Delta protein. As another example, and not by way of limitation, a recombinant molecule can be conεtructed according to the invention, compriεing coding portions of both Delta and another toporythmic gene, e.g., Serrate. The encoded protein of such a recombinant molecule could exhibit properties asεociated with both Serrate and Delta and portray a novel profile of biological activities, including agonistε aε well aε antagoniεtε. The primary εequence of Delta and Serrate may also be uεed to predict tertiary structure of the molecules using computer simulation (Hopp and Woods, 1981, Proc. Natl. Acad. Sci. U.S.A. 78:3824-3828); Delta/Serrate chimeric recombinant genes could be designed in light of correlations between tertiary εtructure and biological function. Likewise, chimeric genes comprising portions of Delta fused to any heterologouε protein-encoding εequences may be constructed. A specific embodiment relates to a chimeric protein compriεing a fragment of Delta of at least six amino acids. In another specific embodiment, the Delta derivative is a fragment of vertebrate Delta compriεing a region of homology with another toporythmic protein. Aε uεed herein, a region of a firεt protein εhall be considered "homologous" to a second protein when the amino acid εequence of the region iε at leaεt 30% identical or at leaεt 75% either identical or involving conεervative changes, when compared to any sequence in the second protein of an equal number of amino acidε aε the number contained in the region. For example, such a Delta fragment can comprise one or more regions homologous to Serrate, including but not limited to the DSL domain or a portion thereof. Other specific embodimentε of derivativeε and analogε are deεcribed in the εubεectionε below and exampleε εectionε infra . 5.6.1. DERIVATIVES OF DELTA CONTAINING ONE OR MORE DOMAINS OF THE PROTEIN In a εpecific embodiment, the invention relateε to vertebrate Delta derivativeε and analogε, in particular Delta fragmentε and derivativeε of such fragments, that comprise, or alternatively consiεt of, one or more domainε of the Delta protein, including but not limited to the extracellular domain, signal sequence, region amino-terminal to the DSL domain, DSL domain, ELR domain, transmembrane domain, intracellular domain, and one or more of the EGF-like repeats (ELR) of the Delta protein (e.g., ELRs 1-9) , or any combination of the foregoing. In particular exampleε relating to the chick and mouεe Delta proteins, such domainε are identified in Exampleε Section 6 and 7, reεpectively, and in Figures 3 and 9. Thus, by way of example is provided, a molecule comprising an extracellular domain (approximately amino acids 1-545) , signal εequence (approximately amino acids 1-17) , region amino-terminal to the DSL domain (approximately amino acids 1-178) , the DSL domain (approximately amino acids 179-223), EGF1 (approximately amino acids 229-260) , EGF2 (approximately amino acids 261- 292), EGF3 (approximately amino acids 293-332), EGF4 (approximately amino acids 333-370) , EGF5 (approximately amino acids 371-409) , EGF6 (approximately amino acidε 410- 447), EGF7 (approximately amino acidε 448-485), EGF8 (approximately amino acidε 486-523) , tranεmembrane domain, and intracellular (cytoplasmic) domain (approximately amino acidε 555-728) of a vertebrate Delta. In a εpecific embodiment, the moleculeε compriεing εpecific fragmentε of vertebrate Delta are thoεe compriεing fragments in the reεpective Delta protein moεt homologouε to εpecific fragmentε of the Drosophila or chick Delta protein. In particular embodiments, such a molecule compriseε or consists of the amino acid sequenceε of SEQ ID NO:2 or 16. Alternatively, a fragment compriεing a domain of a Delta homolog can be identified by protein analyεiε methods as described in Section 5.3.2. 5.6.2. DERIVATIVES OF DELTA THAT MEDIATE BINDING TO TOPORYTHMIC PROTEIN DOMAINS The invention also provides for vertebrate Delta fragments, and analogs or derivatives of such fragments, which mediate binding to toporythmic proteins (and thus are termed herein "adhesive"), and nucleic acid εequenceε encoding the foregoing. In a particular embodiment, the adheεive fragment of a Delta protein compriεeε the DSL domain, or a portion thereof. Subfragmentε within the DSL domain that mediate binding to Notch can be identified by analyεiε of constructs expresεing deletion mutants. The ability to bind to a toporythmic protein (preferably Notch) can be demonεtrated by in vitro aggregation aεεayε with cells expresεing εuch a toporythmic protein aε well as cells expresεing Delta or a Delta derivative (See Section 5.7) . That is, the ability of a Delta fragment to bind to a Notch protein can be demonstrated by detecting the ability of the Delta fragment, when expresεed on the εurface of a first cell, to bind to a Notch protein expresεed on the surface of a second cell. The nucleic acid sequences encoding toporythmic proteins or adhesive domains thereof, for use in such asεayε, can be iεolated from human, porcine, bovine, feline, avian, equine, canine, or inεect, aε well aε primate εourceε and any other εpecieε in which homologs of known toporythmic genes can be identified. 5.7. ASSAYS OF DELTA PROTEINS, DERIVATIVES AND ANALOGS The functional activity of vertebrate Delta proteins, derivatives and analogε can be asεayed by various methods. For example, in one embodiment, where one is assaying for the ability to bind or compete with wild-type Delta for binding to anti-Delta antibody, various immunoassays known in the art can be used, including but not limited to competitive and non-competitive asεay systems using techniques εuch aε radioimmunoaεεayε, ELISA (enzyme linked immunoεorbent assay) , "sandwich" immunoasεayε, immunoradiometric aεεayε, gel diffuεion precipitin reactionε, immunodiffuεion aεεayε, in situ immunoaεsays (using colloidal gold, enzyme or radioisotope labels, for example) , western blotε, precipitation reactions, agglutination asεayε (e.g., gel agglutination aεεays, hemagglutination asεays) , complement fixation asεayε, immunofluoreεcence assays, protein A aεεays, and immunoelectrophoresiε aεεays, etc. In one embodiment, antibody binding iε detected by detecting a label on the primary antibody. In another embodiment, the primary antibody is detected by detecting binding of a secondary antibody or reagent to the primary antibody. In a further embodiment, the secondary antibody is labelled. Many means are known in the art for detecting binding in an immunoasεay and are within the scope of the present invention. In another embodiment, where one is asεaying for the ability to mediate binding to a toporythmic protein, e.g., Notch, one can carry out an in vitro aggregation aεsay (see Fehon et al., 1990, Cell 61:523-534; Rebay et al., 1991, Cell 67:687-699) . In another embodiment, where a receptor for Delta is identified, receptor binding can be assayed, e.g., by means well-known in the art. In another embodiment, physiological correlates of Delta binding to cells expresεing a Delta receptor (εignal tranεduction) can be aεεayed. In another embodiment, in insect or other model systems, genetic studieε can be done to study the phenotypic effect of a Delta mutant that is a derivative or analog of wild-type Delta . Other methods will be known to the skilled artisan and are within the εcope of the invention. 5.8. THERAPEUTIC USES The invention provideε for treatment of diεorders of cell fate or differentiation by adminiεtration of a therapeutic compound of the invention. Such therapeutic compoundε (termed herein "Therapeuticε") include: Delta proteins and analogs and derivatives (including fragmentε) thereof (e.g., aε deεcribed hereinabove); antibodieε thereto (aε deεcribed hereinabove) ; nucleic acidε encoding the Delta proteins, analogs, or derivativeε (e.g., aε deεcribed hereinabove); and Delta antiεenεe nucleic acidε. Aε εtated supra , the Antagoniεt Therapeuticε of the invention are thoεe Therapeuticε which antagonize, or inhibit, a Delta function and/or Notch function (εince Delta iε a Notch ligand) . Such Antagonist Therapeutics are moεt preferably identified by use of known convenient in vitro aεεayε, e.g., based on their ability to inhibit binding of Delta to another protein (e.g., a Notch protein) , or inhibit any known Notch or Delta function as preferably asεayed in vitro or in cell culture, although genetic aεεays {e . g. , in Drosophila ) may also be employed. In a preferred embodiment, the Antagonist Therapeutic iε a protein or derivative thereof compriεing a functionally active fragment such as a fragment of Delta which mediates binding to Notch, or an antibody thereto. In other specific embodimentε, εuch an Antagoniεt Therapeutic is a nucleic acid capable cf expresεing a molecule compriεing a fragment of Delta which bindε to Notch, or a Delta antisense nucleic acid (see Section 5.11 herein). It εhould be noted that preferably, εuitable in vitro or in vivo aεsays, as described infra , should be utilized to determine the effect of a specific Therapeutic and whether its administration is indicated for treatment of the affected tissue, since the developmental history of the tisεue may determine whether an Antagonist or Agonist Therapeutic is desired. In addition, the mode of administration, e.g., whether administered in εoluble form or administered via its encoding nucleic acid for intracellular recombinant expression, of the Delta protein or derivative can affect whether it acts as an agonist or antagonist. In another embodiment of the invention, a nucleic acid containing a portion of a Delta gene is used, as an Antagonist Therapeutic, to promote Delta inactivation by homologous recombination (Koller and Smithies, 1989, Proc. Natl. Acad. Sci. USA 86:8932-8935; Zijlstra et al. , 1989, Nature 342:435-438). The Agoniεt Therapeuticε of the invention, aε described εupra , promote Delta function. Such Agoniεt Therapeuticε include but are not limited to proteinε and derivativeε comprising the portions of Notch that mediate binding to Delta, and nucleic acidε encoding the foregoing (which can be adminiεtered to expreεs their encoded productε in vivo) . Further deεcriptionε and εourceε of Therapeuticε of the inventionε are found in Sections 5.1 through 5.7 herein. Molecules which retain, or alternatively inhibit, a deεired Delta property, e.g., binding to Notch, binding to an intracellular ligand, can be uεed therapeutically as inducers, or inhibitors, respectively, of εuch property and itε phyεiological correlates. In a specific embodiment, a peptide (e.g., in the range of 6-50 or 15-25 amino acids; and particularly of about 10, 15, 20 or 25 amino acids) containing the sequence of a portion of Delta which binds to Notch iε uεed to antagonize Notch function. In a specific embodiment, such an Antagonist Therapeutic is used to treat or prevent human or other malignancies aεεociated with increased Notch expresεion (e.g., cervical cancer, colon cancer, breaεt cancer, εquamouε adenocarcimaε (εee infra) ) . Derivativeε or analogε of Delta can be teεted for the deεired activity by procedureε known in the art, including but not limited to the aεεayε deεcribed in the examples infra . For example, moleculeε compriεing Delta fragmentε which bind to Notch EGF-repeatε (ELR) 11 and 12 and which are εmaller than a DSL domain, can be obtained and selected by expresεing deletion mutants and assaying for binding of the expresεed product to Notch by any of the εeveral methodε (e.g., in vitro cell aggregation aεεayε, interaction trap εyεtem) , εome of which are deεcribed in the Exampleε Sectionε infra . In one εpecific embodiment, peptide librarieε can be εcreened to εelect a peptide with the deεired activity; εuch screening can be carried out by asεaying, e.g. , for binding to Notch or a molecule containing the Notch ELR 11 and 12 repeats. Other Therapeutics include moleculeε that bind to a vertebrate Delta protein. Thuε, the invention alεo provides a method for identifying such molecules. Such moleculeε can be identified by a method compriεing contacting a plurality of moleculeε (e.g., in a peptide library, or combinatorial chemical library) with the Delta protein under conditionε conducive to binding, and recovering any moleculeε that bind to the Delta protein. The Agonist and Antagonist Therapeuticε of the invention have therapeutic utility for diεorders of cell fate. The Agonist Therapeutics are administered therapeutically (including prophylactically) : (1) in diseases or disorderε involving an absence or decreased (relative to normal, or desired) levels of Notch or Delta function, for example, in patients where Notch or Delta protein iε lacking, genetically defective, biologically inactive or underactive, or underexpresεed; and (2) in diεeases cr disorderε wherein in vitro (or in vivo) assays (see infra) indicate the utility of Delta agonist administration. The abεence or decreaεed levelε in Notch or Delta function can be readily detected, e.g., by obtaining a patient tissue sample (e.g., from biopsy tissue) and asεaying it in vitro for protein levelε, εtructure and/or activity of the expresεed Notch or Delta protein. Many methods standard in the art can be thus employed, including but not limited to immunoasεays to detect and/or visualize Notch or Delta protein (e.g., Weεtern blot, immunoprecipitation followed by sodium dodecyl sulfate polyacrylamide gel electrophoresiε, im unocytochemiεtry, etc.) and/or hybridization aεsays to detect Notch or Delta expression by detecting and/or visualizing respectively Notch or Delta mRNA (e.g., Northern assayε, dot blotε, in εitu hybridization, etc.) Jn vitro aεεays which can be uεed to determine whether adminiεtration of a εpecific Agoniεt Therapeutic or Antagoniεt Therapeutic iε indicated, include in vitro cell culture aεεayε in which a patient tisεue sample is grown in culture, and expoεed to or otherwiεe adminiεtered a Therapeutic, and the effect of εuch Therapeutic upon the tiεεue sample iε obεerved. In one embodiment, where the patient haε a malignancy, a εample of cellε from εuch malignancy is plated out or grown in culture, and the cells are then expoεed to a Therapeutic. A Therapeutic which inhibits survival or growth of the malignant cells (e.g., by promoting terminal differentiation) is selected for therapeutic use in vivo . Many aεεayε εtandard in the art can be used to asseεε εuch εurvival and/or growth; for example, cell proliferation can be aεsayed by measuring 3 H-thymidine incorporation, by direct cell count, by detecting changes in transcriptional activity of known genes such as proto- oncogenes (e.g., foε, myc) or cell cycle markers; cell viability can be asseεεed by trypan blue εtaining, differentiation can be aεεeεsed viεually baεed on changeε in morphology, etc. In a specific aspect, the malignant cell cultures are separately exposed to (1) an Agonist Therapeutic, and (2) an Antagonist Therapeutic; the result of the aεεay can indicate which type of Therapeutic haε therapeutic efficacy. In another embodiment, a Therapeutic is indicated for use which exhibits the desired effect, inhibition or promotion of cell growth, upon a patient cell εample from tisεue having or εuεpected of having a. hyper- or hypoproliferative diεorder, reεpectively. Such hyper- or hypoproliferative diεorderε include but are not limited to thoεe deεcribed in Sectionε 5.8.1 through 5.8.3 infra . In another εpecific embodiment, a Therapeutic iε indicated for uεe in treating nerve injury or a nervous syεtem degenerative diεorder (εee Section 5.8.2) which exhibits in vitro promotion of nerve regeneration/neurite extension from nerve cellε of the affected patient type. In addition, adminiεtration of an Antagonist Therapeutic of the invention is alεo indicated in diεeaεeε or disorders determined or known to involve a Notch or Delta dominant activated phenotype ("gain of function" mutations.) Administration of an Agonist Therapeutic is indicated in diεeaεeε or diεorderε determined or known to involve a Notch or Delta dominant negative phenotype ("loss of function" mutationε) . The functions of various structural domains of the Notch protein have been investigated in vivo , by ectopically expresεing a series of Droεophila Notch deletion mutants under the hsp70 heat-shock promoter, as well as eye- specific promoters (see Rebay et al., 1993, Cell 74:319-329). Two clasεeε of dominant phenotypeε were obεerved, one εuggestive of Notch losε-of function mutations and the other of Notch gain-of-function mutations. Dominant "activated" phenotypes resulted from overexpresεion of a protein lacking moεt extracellular sequences, while dominant "negative" phenotypes resulted from overexpreεεion of a protein lacking moεt intracellular sequences. The results indicated that Notch functions aε a receptor whoεe extracellular domain mediateε ligand-binding, resulting in the transmiεεion of developmental εignalε by the cytoplaεmic domain. In variouε εpecific embodimentε, in vitro aεεayε can be carried out with repreεentative cellε of cell typeε involved in a patient'ε disorder, to determine if a Therapeutic haε a desired effect upon such cell types. In another embodiment, cells of a patient tiεsue sample suεpected of being pre-neoplaεtic are εimilarly plated out or grown in vitro , and expoεed to a Therapeutic. The Therapeutic which reεultε in a cell phenotype that iε more normal (i.e., less representative of a pre-necplaεtic state, neoplastic state, malignant state, or transformed phenotype) is εelected for therapeutic use. Many asεayε εtandard in the art can be uεed to aεεesε wnether a pre-neoplastic state, neoplastic state, or a transformed cr malignant phenotype, is present. For example, characteristicε aεεociated with a transformed phenotype (a set of in vitro characteristics asεociated with a tumorigenic ability in vivo) include a more rounded cell morphology, looεer substratum attachment, loss of contact inhibition, loεε of anchorage dependence, releaεe of proteaεes such as plasminogen activator, increaεed εugar tranεport, decreaεed serum requirement, expresεion of fetal antigenε, diεappearance of the 250,000 dalton εurface protein, etc. (εee Luria et al. , 1978, General Virology, 3d Ed., John Wiley & Sons, New York pp. 436-446). In other specific embodiments, the in vitro asεayε deεcribed εupra can be carried out using a cell line, rather than a cell sample derived from the specific patient to be treated, in which the cell line is derived from or displayε characteriεtic(s) associated with the malignant, neoplastic or pre-neoplastic disorder desired to be treated or prevented, or is derived from the neural or other cell type upon which an effect is desired, according to the present invention. The Antagonist Therapeutics are administered therapeutically (including prophylactically) : (1) in diεeaεes or diεorderε involving increaεed (relative to normal, or deεired) levels of Notch or Delta function, for example, where the Notch or Delta protein is overexpreεεed or overactive; and (2) in diεeaεeε or disorders wherein in vitro (or in vivo) assays indicate the utility of Delta antagonist administration. The increaεed levelε of Notch or Delta function can be readily detected by methodε εuch aε those described above, by quantifying protein and/or RNA. In vitro aεεayε with cellε of patient tiεεue εample or the appropriate cell line or cell type, to determine therapeutic utility, can be carried out aε deεcribed above. 5.8.1. MALIGNANCIES Malignant and pre-neoplaεtic conditionε which can be tested as described supra for efficacy of intervention with Antagonist or Agonist Therapeutics, and which can be treated upon thus obεerving an indication of therapeutic utility, include but are not limited to thoεe deεcribed below in Sectionε 5.8.1 and 5.9.1. Malignancieε and related disorders, cells of which type can be tested in vitro (and/or in vivo) , and upon observing the appropriate assay result, treated according to the present invention, include but are not limited to those listed in Table 1 (for a review of such diεorderε, εee Fiεh an et al., 1985, Medicine , 2d Ed., J.B. Lippincott Co., Philadelphia) : TABLE 1 MALIGNANCIES AND RELATED DISORDERS Leukemia acute leukemia acute lymphocytic leukemia acute myelocytic leukemia myeloblaεtic promyelocytic myelomonocytic monocytic erythroleukemia chronic leukemia chronic myelocytic (granulocytic) leukemia chronic lymphocytic leukemia Polycythemia vera Lymphoma Hodgkin's diseaεe non-Hodgkin'ε diεeaεe Multiple myeloma Waldenεtrδm'ε macroglobulinemia Heavy chain diεease Solid tumors sarcomas and carcinomas fibrosarcoma myxosarcoma lipoεarcoma chondrosarcoma osteogenic sarcoma chordoma angioεarcoma endotheliosarcoma lymphangiosarcoma lymphangioendotheliosarcoma synovioma mesothelioma Ewing'ε tumor leiomyoεarcoma rhabdomyoεarcoma colon carcinoma pancreatic cancer breast cancer ovarian cancer prostate cancer squamous cell carcinoma basal cell carcinoma adenocarcinoma sweat gland carcinoma sebaceouε gland carcinoma papillary carcinoma papillary adenocarcinomas cystadenocarcinoma medullary carcinoma bronchogenic carcinoma renal cell carcinoma hepatoma bile duct carcinoma choriocarcinoma seminoma embryonal carcinoma Wilms' tumor cervical cancer testicular tumor lung carcinoma small cell lung carcinoma bladder carcinoma epithelial carcinoma glioma astrocytoma medulloblaεtoma craniopharyngioma ependymoma pinealoma hemangioblaεtoma acoustic neuroma oligodendroglioma menangioma melanoma neuroblastoma retinoblastoma In specific embodiments, malignancy or dysproliferative changes (such aε metaplaεiaε and dyεplasias) are treated or prevented in epithelial tisεueε εuch aε those in the cervix, eεophagus, and lung. Malignancies of the colon and cervix exhibit increaεed expreεsion of human Notch relative to such non- malignant tisεue (εee PCT Publication no. WO 94/07474 publiεhed April 14, 1994, incorporated by reference herein in itε entirety) . Thus, in εpecific embodiments, malignancies or premalignant changes of the colon or cervix are treated or prevented by administering an effective amount of an Antagonist Therapeutic, e.g., a Delta derivative, that antagonizes Notch function. The preεence of increased Notch expresεion in colon, and cervical cancer εuggests that many more cancerous and hyperproliferative conditions exhibit upregulated Notch. Thus, in εpecific embodiments, variouε cancers, e . g. , breast cancer, squamous adenocarcinoma, seminoma, melanoma, and lung cancer, and premalignant changes therein, as well aε other hyperproliferative disorders, can be treated or prevented by adminiεtration of an Antagonist Therapeutic that antagonizeε Notch function. 5.8.2. NERVOUS SYSTEM DISORDERS Nervouε εystem disorders, involving cell types which can be tested as described supra for efficacy of intervention with Antagonist or Agonist Therapeutics, and which can be treated upon thus observing an indication of therapeutic utility, include but are not limited to nervous εystem injuries, and diεeases or disorderε which reεult in either a diεconnection of axons, a diminution or degeneration of neurons, or demyelination. Nervous system lesionε which may be treated in a patient (including human and non-human mammalian patientε) according to the invention include but are not limited to the following lesions of either the central (including spinal cord, brain) or peripheral nervous syεtemε: (i) traumatic leεionε, including leεions caused by physical injury or aεsociated with surgery, for example, lesions which sever a portion of the nervous syεtem, or compresεion injuries; (ii) iεchemic leεions, in which a lack of oxygen in a portion of the nervous system resultε in neuronal injury or death, including cerebral infarction or ischemia, or spinal cord infarction or ischemia; (iii) malignant lesionε, in which a portion of the nervouε εyεtem iε destroyed or injured by malignant tisεue which iε either a nervous syεtem aεεociated malignancy or a malignancy derived from non-nervous syεtem tiεεue; (iv) infectious lesionε, in which a portion of the nervouε εystem is destroyed or injured as a result of infection, for example, by an abεcess or asεociated with infection by human immunodeficiency virus, herpes zoster, or herpes simplex virus or with Lyme diseaεe, tuberculoεis, syphilis; (v) degenerative lesions, in which a portion of the nervous system is destroyed or injured aε a result of a degenerative proceεs including but not limited to degeneration asεociated with Parkinεon's diεease, Alzheimer's diεeaεe, Huntington's chorea, or amyotrophic lateral scleroεiε; (vi) leεionε aεsociated with nutritional diseases or disorderε, in which a portion of the nervouε εystem iε destroyed or injured by a nutritional disorder or diεorder of metaboliεm including but not limited to, vitamin B12 deficiency, folic acid deficiency, Wernicke diεease, tobacco-alcchol a blyopia, Marchiafava-Bigna i disease (primary degeneration of the corpus calloεum) , and alcoholic cerebellar degeneration; (vii) neurological lesions associated vith syεtemic diseaεeε including but not limited to diabetes (diabetic neuropathy, Bell's palsy) , εyεtemic lupus erythe atosuε, carcinoma, or εarcoidoεis; (viii) leεionε cauεed by toxic εubεtanceε including alcohol, lead, or particular neurotoxinε; and (ix) demyelinated leεionε in which a portion of the nervouε system is destroyed or injured by a demyelinating diεeaεe including but not limited to multiple εclerosis, human immunodeficiency virus-aεsociated myelopathy, transverse myelopathy or various etiologies, progreεεive multifocal leukoencephalopathy, and central pontine myelinolyεiε. Therapeutics which are useful according to the invention for treatment of a nervous system disorder may be selected by testing for biological activity in promoting the survival or differentiation of neuronε (see also Section 5.8). For example, and not by way of limitation, Therapeuticε which elicit any of the following effectε may be uεeful according to the invention: (i) increaεed εurvival time of neuronε in culture; (ii) increaεed εprouting of neuronε in culture or in vivo; (iii) increaεed production of a neuron-aεεociated molecule in culture or in vivo , e . g . , choline acetyltransferase or acetylcholineεterase with respect to motor neuronε; or (iv) decreaεed εymptomε of neuron dyεfunction in vivo. Such effects may be measured by any method known in the art. In preferred, non-limiting embodiments, increased survival of neurons may be meaεured by the method εet forth in Arakawa et al. (1990, J. Neuroεci. 10:3507-3515); increaεed εprouting of neurons may be detected by methodε εet forth in Pestronk et al. (1980, Exp. Neurol. 70:65-82) or Brown et al. il981, Ann. Rev. Neurosci. 4:17-42); increased production of neuron- associated moleculeε may be meaεured by bioaεεay, enzymatic aεεay, antibody binding, Northern blot assay, etc. , depending on the molecule to be measured; and motor neuron dysfunction may be measured by aεsesεing the phyεical manifeεtation of motor neuron diεorder, e.g., weakneεs, motor neuron conduction velocity, or functional disability. In a specific embodimentε, motor neuron diεorderε that may be treated according to the invention include but are not limited to diεorderε εuch aε infarction, infection, expoεure to toxin, trauma, surgical damage, degenerative disease or malignancy that may affect motor neurons as well as other components of the nervous system, as well as disorders that selectively affect neurons such as amyotrophic lateral scleroεiε, and including but not limited to progreεεive εpinal muεcular atrophy, progreεεive bulbar palεy, primary lateral scleroεiε, infantile and juvenile muεcular atrophy, progreεsive bulbar paralysis of childhood (Fazio-Londe syndrome) , poliomyelitis and the post polio εyndrome, and Hereditary Motorsensory Neuropathy (Charcot- Marie-Tooth Diseaεe) . 5.8.3. TISSUE REPAIR AND REGENERATION In another embodiment of the invention, a Therapeutic of the invention iε uεed for promotion of tiεsue regeneration and repair, including but not limited to treatment of benign dyεproliferative diεorders. Specific embodiments are directed to treatment of cirrhosiε of the liver (a condition in which εcarring haε overtaken normal liver regeneration processeε) , treatment of keloid (hypertrophic scar) formation (disfiguring of the skin in which the scarring procesε interferes with normal renewal) , psoriasiε (a common skin condition characterized by excesεive proliferation of the εkin and delay in proper cell fate determination) , and baldness (a condition in which terminally differentiated hair follicles (a tisεue rich in Notch) fail to function properly) . In another embodiment, a Therapeutic of the invention iε uεed to treat degenerative or traumatic diεorderε of the εenεory epithelium of the inner ear. 5.9. PROPHYLACTIC USES 5.9.1. MALIGNANCIES The Therapeuticε of the invention can be adminiεtered to prevent progreεεion to a neoplastic or malignant state, including but not limited to those disorderε listed in Table 1. Such administration is indicated where the Therapeutic is shown in assays, as described supra , to have utility for treatment or prevention of such diεorder. Such prophylactic use is indicated in conditions known or suspected of preceding progression to neoplasia or cancer, in particular, where non-neoplastic cell growth conεisting of hyperplasia, metaplasia, or most particularly, dysplasia has occurred (for review of such abnormal growth conditions, see Robbins and Angell, 1976, Basic Pathology, 2d Ed., W.B. Saunders Co., Philadelphia, pp. 68-79.) Hyperplasia is a form of controlled cell proliferation involving an increase in cell number in a tissue or organ, without significant alteration in structure or function. As but one example, endometrial hyperplaεia often precedes endometrial cancer. Metaplasia is a form of controlled cell growth in which one type of adult or fully differentiated cell εubεtituteε for another type of adult cell. Metaplaεia can occur in epithelial or connective tiεεue cellε. Atypical metaplaεia involveε a εomewhat diεorderly metaplastic epithelium. Dysplasia iε frequently a forerunner of cancer, and iε found mainly in the epithelia; it iε the moεt diεorderly form of non-neoplaεtic cell growth, involving a loss in individual cell uniformity and in the architectural orientation of cells. Dysplaεtic cellε often have abnormally large, deeply stained nuclei, and exhibit pleornorphism. Dysplasia characteristically occurs where there exiεts chronic irritation or inflammation, and is often found in the cervix, respiratory passages, oral cavity, and gall bladder. Alternatively or in addition to the presence of abnormal cell growth characterized as hyperplasia, metaplasia, or dysplasia, the presence of one or more characteristics of a transformed phenotype, or of a malignant phenotype, displayed in vivo or displayed in vitro by a cell sample from a patient, can indicate the desirability of prophylactic/therapeutic administration of a Therapeutic of the invention. As mentioned supra , εuch characteriεtics of a transformed phenotype include morphology changeε, looεer εubstratum attachment, loss of contact inhibition, losε of anchorage dependence, proteaεe releaεe, increased sugar tranεport, decreaεed εerum requirement, expreεεion of fetal antigenε, diεappearance of the 250,000 dalton cell εurface protein, etc. (see alεo id . , at pp. 84-90 for characteriεticε associated with a transformed or malignant phenotype) . In a εpecific embodiment, leukoplakia, a benign- appearing hyperplaεtic or dysplastic leεion of the epithelium, or Bowen'ε diεease, a carcinoma in situ , are pre- neoplaεtic lesions indicative of the desirability of prophylactic intervention. In another embodiment, fibrocystic diεeaεe (cyεtic hyperplaεia, mammary dysplasia, particularly adenosiε (benign epithelial hyperplaεia) ) iε indicative of the deεirability of prophylactic intervention. In other embodimentε, a patient which exhibits one or more of the following predispoεing factorε for malignancy is treated by administration of an effective amount of a Therapeutic: a chromosomal translocation asεociated with a malignancy (e.g., the Philadelphia chromosome for chronic myelogenous leukemia, t(14;18) for follicular lymphoma, etc.), familial polyposiε or Gardner'ε εyndrome (poεεible forerunners of colon cancer) , benign monoclonal gammopathy (a poεεible forerunner of multiple myeloma) , and a firεt degree kinεhip with perεonε having a cancer or precancerouε diεease showing a Mendelian (genetic) inheritance pattern (e.g., familial polyposis of the colon, Gardner'ε εyndrome, hereditary exoεtoεis, polyendocrine adenomatosis, medullary thyroid carcinoma with amyloid production and pheochromocytoma, Peutz-Jeghers syndrome, neurofibro atosiε of Von Recklinghausen, retinoblastoma, carotid body tumor, cutaneous melanocarcinoma, intraocular melanocarcinoma, xeroderma pigmentosum, ataxia telangiectaεia, Chediak-Higaεhi syndrome, albinism, Fanconi's aplastic anemia, and Bloom' εyndrome; see Robbinε and Angell, 1976, Basic Pathology, 2d Ed., W.B. Saunderε Co., Philadelphia, pp. 112-113) etc.) In another εpecific embodiment, an Antagonist Therapeutic of the invention is administered to a human patient to prevent progresεion to breast, colon, or cervical cancer. 5.9.2. OTHER DISORDERS In other embodimentε, a Therapeutic of the invention can be administered to prevent a nervouε system disorder described in Section 5.8.2, or other disorder (e.g., liver cirrhoεiε, psoriasis, keloids, baldnesε) deεcribed in Section 5.8.3. 5.10. DEMONSTRATION OF THERAPEUTIC OR PROPHYLACTIC UTILITY The Therapeutics of the invention can be tested in vivo for the desired therapeutic or prophylactic activity. For example, such compounds can be tested in suitable animal model systems prior to testing in humanε, including but not limited to rats, mice, chicken, cows, monkeys, rabbitε, etc. For in vivo testing, prior to administration to humanε, any animal model system known in the art may be used. 5.11. ANTISENSE REGULATION OF DELTA EXPRESSION The present invention provides the therapeutic or prophylactic use of nucleic acids of at least six nucleotides that are antisenεe to a gene or cDNA encoding Delta or a portion thereof. "Antiεense" as used herein refers to a nucleic acid capable of hybridizing to a portion of a Delta RNA (preferably mRNA) by virtue of some sequence complementarity. Such antiεenεe nucleic acidε have utility aε Antagoniεt Therapeuticε of the invention, and can be uεed in the treatment or prevention of diεorderε aε deεcribed supra in Section 5.8 and its subsections. The antisense nucleic acids of the invention can be oligonucleotides that are double-stranded or single-stranded, RNA or DNA or a modification or derivative thereof, which can be directly administered to a cell, or which can be produced intracellularly by transcription of exogenous, introduced sequenceε. In a specific embodiment, the Delta antisenεe nucleic acids provided by the instant invention can be used for the treatment of tumorε or other disorders, the cells of which tumor type or diεorder can be demonstrated (in vitro or in vivo) to expresε a Delta gene or a Notch gene. Such demonεtration can be by detection of RNA or of protein. The invention further provideε pharmaceutical compositions comprising an effective amount of the Delta antisense nucleic acids of the invention in a pharmaceutically acceptable carrier, aε deεcribed infra in Section 5.12. Methodε for treatment and prevention of diεorders (such as thoεe deεcribed in Sectionε 5.8 and 5.9) comprising administering the pharmaceutical compositions of the invention are also provided. In another embodiment, the invention iε directed to methodε for inhibiting the expreεεion of a Delta nucleic acid sequence in a prokaryotic or eukaryotic cell comprising providing the cell with an effective amount of a composition comprising an antisense Delta nucleic acid of the invention. Delta antisense nucleic acids and their uses are described in detail below. 5.11.1. DELTA ANTISENSE NUCLEIC ACIDS The Delta antisense nucleic acids are of at least six nucleotideε and are preferably oligonucleotideε (ranging from 6 to about 50 oligonucleotideε) . In εpecific aεpects, the oligonucleotide iε at leaεt 10 nucleotideε, at leaεt 15 nucleotideε, at least 100 nucleotides, or at least 200 nucleotides. The oligonucleotides can be DNA or RNA or chimeric mixtures or derivatives or modified versionε thereof, εingle-εtranded or double-εtranded. The oligonucleotide can be modified at the baεe moiety, εugar moiety, or phoεphate backbone. The oligonucleotide may include other appending groupε εuch aε peptideε, or agentε facilitating tranεport acrosε the cell membrane (εee, e.g., Letsinger et al., 1989, Proc. Natl. Acad. Sci. U.S.A. 86:6553-6556; Lemaitre et al., 1987, Proc. Natl. Acad. Sci. 84:648-652; PCT Publication No. WO 88/09810, published December 15, 1988) or blood-brain barrier (see, e . g . , PCT Publication No. WO 89/10134, publiεhed April 25, 1988), hybridization-triggered cleavage agentε (see, e.g., Krol et al., 1988, BioTechniques 6:958-976) or intercalating agents (see, e.g., Zon, 1988, Pharm. Res. 5:539-549) . In a preferred aspect of the invention, a Delta antisenεe oligonucleotide is provided, preferably of single- stranded DNA. In a most preferred aspect, such an oligonucleotide compriseε a εequence antiεenεe to the εequence encoding an SH3 binding domain or a Notch-binding domain of Delta, moεt preferably, of human Delta. The oligonucleotide may be modified at any position on its structure with subεtituents generally known in the art. The Delta antiεenεe oligonucleotide may comprise at least one modified baεe moiety which iε εelected from the group including but not limited to 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xantine, 4-acetylcytoεine, 5-(carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5-carboxymethylarainomethyluracil, dihydrouracil, beta-D- galactoεylqueosine, inoεine, N6-iεopentenyladenine, l-methylguanine, 1-methylinoεine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytoεine, 5-methylcytoεine, N6-adenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannoεylqueoεine, 5 '-methoxycarboxymethyluracil, 5-methoxyuracil, 2-methylthio-N6-iεopentenyladenine, uracil-5-oxyacetic acid (v) , wybutoxoεine, pεeudouracil, queoεine, 2-thiocytoεine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, uracil- 5-oxyacetic acid methyleεter, uracil-5-oxyacetic acid (v) , 5-methyl-2-thiouracil, 3- (3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2, 6-diaminopurine. In another embodiment, the oligonucleotide compriεeε at leaεt one modified εugar moiety εelected from the group including but not limited to arabinoεe, 2-fluoroarabinoεe, xyluloεe, and hexose. In yet another embodiment, the oligonucleotide comprises at least one modified phosphate backbone selected from the group consiεting of a phoεphorothioate, a phoεphorodithioate, a phoεphoramidothioate, a phoεphoramidate, a phoεphordiamidate, a methylphoεphonate, an alkyl phoεphotrieεter, and a formacetal or analog thereof. In yet another embodiment, the oligonucleotide is an α-anomeric oligonucleotide. An α-anomeric oligonucleotide forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual 3-units, the εtrandε run parallel to each other (Gautier et al., 1987, Nucl. Acidε Res. 15:6625-6641). The oligonucleotide may be conjugated to another molecule, e.g., a peptide, hybridization triggered crosε¬ linking agent, transport agent, hybridization-triggered cleavage agent, etc. Oligonucleotides of the invention may be synthesized by εtandard methodε known in the art, e.g. by uεe of an automated DNA εyntheεizer (εuch aε are commercially available from Bioεearch, Applied Biosystems, etc.) . As examples, phosphorothioate oligonucleotides may be synthesized by the method of Stein et al. (1988, Nucl. Acids Res. 16:3209), methylphosphonate oligonucleotideε can be prepared by uεe of controlled pore glaεε polymer εupportε (Sarin et al., 1988, Proc. Natl. Acad. Sci. U.S.A. 85:7448- 7451) , etc. In a εpecific embodiment, the Delta antiεenεe oligonucleotide compriεeε catalytic RNA, or a ribozyme (εee, e.g., PCT International Publication WO 90/11364, publiεhed October 4, 1990; Sarver et al., 1990, Science 247:1222-1225). In another embodiment, the oligonucleotide iε a 2 '-0- methylribonucleotide (Inoue et al., 1987, Nucl. Acidε Res. 15:6131-6148) , or a chimeric RNA-DNA analogue (Inoue et al., 1987, FEBS Lett. 215:327-330). In an alternative embodiment, the Delta antisenεe nucleic acid of the invention is produced intracellularly by transcription from an exogenouε sequence. For example, a vector can be introduced in vivo such that it is taken up by a cell, within which cell the vector or a portion thereof iε tranεcribed, producing an antiεenεe nucleic acid (RNA) of the invention. Such a vector- would contain a εequence encoding the Del ta antisense nucleic acid. Such a vector can remain episomal or become chromosomally integrated, as long as it 5 can be transcribed to produce the desired antisenεe RNA. Such vectors can be constructed by recombinant DNA technology methods standard in the art. Vectors can be plaεmid, viral, or otherε known in the art, used for replication and expression in mammalian cells. Expresεion of the sequence 10 encoding the Delta antisense RNA can be by any promoter known in the art to act in mammalian, preferably human, cells. Such promoterε can be inducible or constitutive. Such promoters include but are not limited to: the SV40 early promoter region (Bernoist and Chambon, 1981, Nature 290:304- 15 310), the promoter contained in the 3' long terminal repeat of Rous sarcoma virus (Yamamoto et al., 1980, Cell 22:787- 797), the herpes thymidine kinase promoter (Wagner et al., 1981, Proc. Natl. Acad. Sci. U.S.A. 78:1441-1445), the regulatory sequences of the metallothionem gene (Brinster et 20 al., 1982, Nature 296:39-42), etc. The antisenεe nucleic acids of the invention comprise a sequence complementary to at least a portion of an RNA transcript of a Delta gene, preferably a human Delta gene. However, absolute complementarity, although preferred, 25 iε not required. A εequence "complementary to at least a portion of an RNA," aε referred to herein, meanε a εequence having εufficient complementarity to be able to hybridize with the RNA, forming a εtable duplex; in the caεe of double- εtranded Delta antiεenεe nucleic acidε, a εingle εtrand of 30 the duplex DNA may thuε be teεted, or triplex formation may be aεεayed. The ability to hybridize will depend on both the degree of complementarity and the length of the antiεenεe nucleic acid. Generally, the longer the hybridizing nucleic acid, the more baεe miεmatcheε with a Delta RNA it may 35 contain and εtill form a εtable duplex (or triplex, aε the caεe may be) . One skilled in the art can ascertain a tolerable degree of miεmatch by use of εtandard procedureε to determine the melting point of the hybridized complex. 5.11.2. THERAPEUTIC UTILITY OF DELTA ANTISENSE NUCLEIC ACIDS The Delta antisense nucleic acids can be used to treat (or prevent) malignancies or other disorderε, of a cell type which has been shown to express Delta or Notch . In specific embodiments, the malignancy is cervical, breast, or colon cancer, or squa ouε adenocarcinoma. Malignant, neoplaεtic, and pre-neoplaεtic cellε which can be teεted for such expresεion include but are not limited to thoεe deεcribed εupra in Sectionε 5.8.1 and 5.9.1. In a preferred embodiment, a εingle-εtranded DNA antiεenεe Delta oligonucleotide iε uεed. Malignant (particularly, tumor) cell typeε which expreεε Delta or Notch RNA can be identified by variouε methodε known in the art. Such methodε include but are not limited to hybridization with a Delta or Wotch-εpecific nucleic acid (e.g. by Northern hybridization, dot blot hybridization, in εitu hybridization) , observing the ability of RNA from the cell type to be translated in vitro into Notch or Delta, immunoassay, etc. In a preferred aεpect, primary tumor tiεεue from a patient can be aεεayed for Notch or Delta expreεsion prior to treatment, e.g., by immunocytochemistry or in εitu hybridization. Pharmaceutical compoεitionε of the invention (εee Section 5.12), compriεing an effective amount of a Delta antiεenεe nucleic acid in a pharmaceutically acceptable carrier, can be adminiεtered to a patient having a malignancy which iε of a type that expreεseε Notch or Delta RNA or protein. The amount of Delta antiεenεe nucleic acid which will be effective in the treatment of a particular disorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques. Where posεible, it iε deεirable to determine the antisense cytotoxicity of the tumor type to be treated in vitro , and then in useful animal model systems prior to testing and use in humanε. In a εpecific embodiment, pharmaceutical compoεitionε comprising Delta antisenεe nucleic acids are administered via liposomes, microparticles, or microcapsules. In various embodiments of the invention, it may be useful to uεe εuch compoεitions to achieve sustained release of the Delta antisenεe nucleic acids. In a specific embodiment, it may be desirable to utilize liposomes targeted via antibodies to specific identifiable tumor antigens (Leonetti et al . , 1990, Proc. Natl. Acad. Sci. U.S.A. 87:2448-2451; Renneisen et al., 1990, J. Biol. Chem. 265:16337-16342). 5.12. THERAPEUTIC/PROPHYLACTIC ADMINISTRATION AND COMPOSITIONS The invention provides methods of treatment (and prophylaxis) by adminiεtration to a subject of an effective amount of a Therapeutic of the invention. In a preferred aεpect, the Therapeutic iε εubεtantially purified. The subject is preferably an animal, including but not limited to animals such aε cowε, pigε, chickenε, etc., and is preferably a mammal, and moεt preferably human. Variouε delivery εyεtemε are known and can be used to adminiεter a Therapeutic of the invention, e.g., encapεulation in lipoεomeε, microparticleε, microcapεules, expreεsion by recombinant cellε, receptor-mediated endocytoεiε (εee, e . g . , Wu and Wu, 1987, J. Biol. Chem. 262:4429-4432), conεtruction of a Therapeutic nucleic acid aε part of a retroviral or ether vector, etc. Methodε of introduction include but are not limited to intradermal, intramuscular, intraperitoneal, intravenouε, subcutaneous, intranasal, epidural, and oral routes. The compounds may be administered by any convenient route, for example by infusion or bolus injection, by abεorption through epithelial or mucocutaneouε liningε (e.g., oral mucoεa, rectal and inteεtinal mucosa, etc.) and may be administered together with other biologically active agents. Administration can be εyεtemic or local. In addition, it may be desirable to introduce the pharmaceutical compositions of the invention into the central nervous syεtem by any εuitable route, including intraventricular and intrathecal injection; intraventricular injection may be facilitated by an intraventricular catheter, for example, attached to a reservoir, such as an Ommaya reεervoir. Pulmonary adminiεtration can alεo be employed, e.g., by uεe of an inhaler or nebulizer, and formulation with an aeroεolizing agent. In a εpecific embodiment, it may be desirable to administer the pharmaceutical compositionε of the invention locally to the area in need of treatment; this may be achieved by, for example, and not by way of limitation, local infusion during surgery, topical application, e.g., in conjunction with a wound dresεing after surgery, by injection, by means of a catheter, by meanε of a suppository, or by means of an implant, εaid implant being of a porous, non-porous, or gelatinous material, including membranes, such aε sialaεtic membranes, or fiberε. In one embodiment, administration can be by direct injection at the site (or former site) of a malignant tumor or neoplastic or pre¬ neoplastic tissue. In another embodiment, the Therapeutic can be delivered in a vesicle, in particular a lipoεome (see Langer, Science 249:1527-1533 (1990); Treat et al. , in Lipoεomeε in the Therapy of Infectious Diseaεe and Cancer, Lopez-Bereεtein and Fidler (eds.), Lisε, New York, pp. 353-365 (1989); Lopez-Bereεtein, ibid . , pp. 317-327; see generally ibid . ) In yet another embodiment, the Therapeutic can be delivered in a controlled releaεe syεtem. In one embodiment, a pump may be uεed (see Langer, supra ; Sefton, CRC Crit. Ref. Biomed. Eng. 14:201 (1987) ; Buchwald et al., Surgery 88:507 (1980); Saudek et al., N. Engl. J. Med. 321:574 (1989)). In another embodiment, polymeric materialε can be uεed (see Medical Applicationε of Controlled Releaεe, Langer and Wiεe (edε.), CRC Pres., Boca Raton, Florida (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley, New York (1984); Ranger and Peppas, J. Macromol. Sci. Rev. Macromol. Chem. 23:61 (1983); see also Levy et al., Science 228:190 (1985); During et al. , Ann. Neurol. 25:351 (1989) ; Howard et al., J. Neuroεurg. 71:105 (1989)) . In yet another embodiment, a controlled releaεe εyεtem can be placed in proximity of the therapeutic target, i.e., the brain, thus requiring only a fraction of the syεtemic doεe (see, e.g., Goodεon, in Medical Applicationε of Controlled Releaεe, supra , vol. 2, pp. 115-138 (1984)). Other controlled releaεe εystems are discusεed in the review by Langer (Science 249:1527-1533 (1990)) . In a εpecific embodiment where the Therapeutic iε a nucleic acid encoding a protein Therapeutic, the nucleic acid can be adminiεtered in vivo to promote expreεεion of itε encoded protein, by constructing it as part of an appropriate nucleic acid expression vector and administering it so that it becomes intracellular, e.g., by use of a retroviral vector (see. U.S. Patent No. 4,980,286), or by direct injection, cr by use of microparticle bombardment (e.g., a gene gun; Biolistic, Dupont) , or coating with lipids or cell-surface receptorε or tranεfecting agentε, or by adminiεtering it in linkage to a homeobox-like peptide which iε known to enter the nucleuε (εee e.g., Joliot et al., 1991, Proc. Natl. Acad. Sci. USA 88:1864-1868), etc. Alternatively, a nucleic acid Therapeutic can be introduced intracellularly and incorporated within hoεt cell DNA for expression, by homologous recombination. In specific embodiments directed to treatment or prevention of particular disorderε, preferably the following forms of adminiεtration are uεed: Preferred Forms of Disorder Administration Cervical cancer Topical Gastrointestinal cancer Oral; intravenous Lung cancer Inhaled; intravenous Leukemia Intravenous; extracorporeal Metastatic carcinomas Intravenous; oral Brain cancer Targeted; intravenous;intrathecal Liver cirrhosiε Oral; intravenous Pεoriaεiε Topical Keloidε Topical Baldneεε Topical Spinal cord injury Targeted; intravenous; intrathecal Parkinεon's diseaεe Targeted; intravenouε; intrathecal Motor neuron diεease Targeted; intravenouε; intrathecal Alzheimer's disease Targeted; intravenouε; intrathecal The present invention also provides pharmaceutical compositionε. Such compositions comprise a therapeutically effective amount of a Therapeutic, and a pharmaceutically acceptable carrier. In a specific embodiment, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term "carrier" refers to a diluent, adjuvant, excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical compoεition is administered intravenously. Saline solutions and aqueous dextrose and glycerol εolutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical excipients include starch, glucoεe, lactoεe, sucrose, gelatin, malt, rice, flour, chalk, εilica gel, sodium stearate, glycerol monoεtearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The compoεition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. These compositionε can take the form of εolutionε, suspensions, emulsion, tablets, pills, capεules, powders, εuεtained-releaεe formulationε and the like. The composition can be formulated as a εuppository, with traditional binders and carrierε such as triglycerides. Oral formulation can include standard carriers εuch aε pharmaceutical gradeε of mannitol, lactose, starch, magnesium εtearate, εodium εaccharine, cellulose, magnesium carbonate, etc. Examples of suitable pharmaceutical carriers are described in "Remington's Pharmaceutical Sciences" by E.W. Martin. Such compositionε will contain a therapeutically effective amount of the Therapeutic, preferably in purified form, together with a suitable amount of carrier so as to provide the form for proper administration to the patient. The formulation should suit the mode oc administration. In a preferred embodiment, the composition is formulated in accordance with routine procedures as a pnarmaceutical compoεition adapted for intravenouε administration to human beings. Typically, compositions for intravenous administration are εolutionε in sterile isotonic aqueous buffer. Where neceεεary, the composition may also include a solubilizing agent and a local anesthetic such as lignocaine to ease pain at the εite of the injection. Generally, the ingredientε are εupplied either εeparately or mixed together in unit doεage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an ampoule or sachette indicating the quantity of active agent. Where the composition is to be administered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or εaline. Where the composition is administered by injection, an ampoule of sterile water for injection or εaline can be provided so that the ingredients may be mixed prior to administration. The Therapeutics of the invention can be formulated as neutral or salt formε. Pharmaceutically acceptable εaltε include those formed with free amino groups such as those derived from hydrochloric, phoεphoric, acetic, oxalic, tartaric acidε, etc., and those formed with free carboxyl groups such as those derived from εodium, potaεεiu , ammonium, calcium, ferric hydroxideε, iεopropylamine, triethylamine, 2-ethylamino ethanol, hiεtidine, procaine, etc. The amount of the Therapeutic of the invention which will be effective in the treatment of a particular diεorder or condition will depend on the nature of the diεorder or condition, and can be determined by εtandard clinical techniqueε. In addition, in vitro aεεayε may optionally be employed to help identify optimal doεage rangeε. The preciεe doεe to be employed in the formulation will alεo depend on the route of adminiεtration, and the εeriouεness of the disease or disorder, and should be decided according to the judgment of the practitioner and each patient's circumstanceε. However, εuitable doεage rangeε for intravenous administration are generally about 20-500 micrograms of active compound per kilogram body weight. Suitable doεage ranges for intranasal adminiεtration are generally about 0.01 pg/kg body weight to 1 mg/kg body weight. Effective doεeε may be extrapolated from doεe- reεponεe curves derived from in vitro or animal model test systems. Suppositorieε generally contain active ingredient in the range of 0.5% to 10% by weight; oral formulationε preferably contain 10% to 95% active ingredient. The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredientε of the pharmaceutical compoεitionε of the invention. Optionally aεεociated with εuch container(s) can be a notice in the form preεcribed by a governmental agency regulating the manufacture, uεe or εale of pharmaceuticalε or biological productε, which notice reflectε approval by the agency of manufacture, use or sale for human administration. 5.13. DIAGNOSTIC UTILITY Delta proteins, analogues, derivatives, and subsequences thereof, Delta nucleic acids (and sequenceε complementary thereto) , anti-Delta antibodieε, have uses in diagnostics. Such molecules can be used in asεayε, εuch as immunoasεays, to detect, prognose, diagnoεe, or monitor variouε conditionε, diεeaεeε, and diεorders affecting Delta expression, or monitor the treatment thereof. In particular, such an immunoasεay is carried out by a method comprising contacting a sample derived from a patient with an anti-Delta antibody under conditionε εuch that immunospecific binding can occur, and detecting or measuring the amount of any immunospecific binding by the antibody. In a εpecific aspect, εuch binding of antibody, in tissue sectionε, preferably in conjunction with binding of anti-Notch antibody can be uεed to detect aberrant Notch and/or Delta localization or aberrant levels of Notch-Delta colocalization in a diεease state. In a specific embodiment, antibody to Delta can be uεed to assay in a patient tissue or serum sample for the presence of Delta where an aberrant level of Delta iε an indication of a diseased condition. Aberrant levels of Delta binding ability in an endogenous Notch protein, or aberrant levelε of binding ability to Notch (or other Delta ligand) in an endogenouε Delta protein may be indicative of a disorder of cell fate (e.g., cancer, etc.) By "aberrant levels," iε meant increaεed or decreaεed levelε relative to that preεent, or a standard level representing that present, in an analogous sample from a portion of the body or from a εubject not having the disorder. The immunoassayε which can be uεed include but are not limited to competitive and non-competitive aεεay systemε uεing techniqueε εuch as western blots, radioim unoasεayε, ELISA (enzyme linked immunoεorbent aεsay) , "sandwich" immunoasεays, immunoprecipitation assayε, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion asεays, agglutination aεεays, complement- fixation assays, immunoradiometric assays, fluorescent immunoasεays, protein A immunoassays, to name but a few. Delta genes and related nucleic acid sequenceε and εubεequences, including complementary εequenceε, and other toporythmic gene sequences, can also be used in hybridization aεεays. Delta nucleic acid sequences, or subsequences thereof comprising about at least 8 nucleotideε, can be used as hybridization probeε. Hybridization aεεays can be used to detect, prognoεe, diagnoεe, or monitor conditions, disorderε, or diεease states asεociated with aberrant changeε in Delta expreεεion and/or activity as described supra . In particular, such a hybridization asεay is carried out by a method comprising contacting a sample containing nucleic acid with a nucleic acid probe capable of hybridizing to Del ta DNA or RNA, under conditions such that hybridization can occur, and detecting or measuring any resulting hybridization. Additionally, since Delta bindε to Notch, Delta or a binding portion thereof can be uεed to aεsay for the presence and/or amounts of Notch in a sample, e.g., in screening for malignancies which exhibit increased Notch expreεεion εuch aε colon and cervical cancers. A DELTA HOMOLOG IN THE CHICK IS EXPRESSED IN PROSPECTIVE NEURONS As described herein, we have iεolated and characterized a chick Delta homologue, C-Delta-1 . We εhow that C-Delta-1 is expresεed in prospective neurons during neurogenesis, as new cells are being born and their fates decided. Our data in the chick, suggest that both the Delta/Notch signalling mechanism and itε role in neurogeneεis have been conserved in vertebrateε. 6 -l- CLONING OF C-DELTA-1 We identified a chick Delta homologue, C-Delta-1 , using the polymerase chain reaction (PCR) and degenerate oligonucleotide primers (Figures la, lb and 2, SEQ ID NOS:l, 2, 3 and 4) . C-Delta-1 was cloned by PCR using the degenerate oligonucleotide primers TTCGGITT(C/T)ACITGGCCIGGIAC (SEQ ID NO:19) and TCIATGCAIGTICCICC(A/G)TT (SEQ ID NO:20) which correspond to the fly Delta protein εequenceε FGFTWPGT (SEQ ID NO:21) and NGGTCID (SEQ ID NO:22), reεpectively (Vassin et al., 1987, EMBO J. 6:3431-3440; Kopczynski et al. , 1988, Geneε Dev. 2:1723-1735) . The initial reaction uεed 50ng of firεt-εtrand oligo-d(T) -primed cDNA from εtage 4-6 embryos, lμg of each primer, 0.2mM dNTPε, 2U. of Taq polymeraεe, in 50μl of the εupplied buffer (Perkin-Elmer) . 40 cycleε of amplification were performed at 94°C/30sec; 50°C/2min; 72 * C/2min. Amplified DNA fragmentε were εeparated on an agaroεe gel, cloned in Bluescript pKS " (Stratagene) and εequenced. Two Delta homologε were identified, one of which (C-Deita-1 ) is expressed in the nervous system. Of the homolog that iε expreεsed in the nervouε εystem, two variants were identified that differ at the carboxy-terminal end of the encoded protein due to an alternative splicing event at the 3' end of the C-Delta-1 gene. One encoded protein has 12 extra amino acids at the carboxy-terminal end, relative to the other encoded protein. The sequence of the shorter encoded variant iε εet forth in SEQ ID NO:2. The longer variant encoded by SEQ ID NO:3 and identified by the amino acid εequence of SEQ ID NO:4, conεists of the amino acid sequence of SEQ ID NO:2 plus twelve additional amino acidε at the 3' end (SIPPGSRTSLGV) . The longer variant waε uεed in the experimentε deεcribed below. When teεted for biological activity by injection of RNA into Xenopus oocytes, each of the variants had the same biological activity. DNA fragmentε correεponding to C-Delta-1 were used to screen a εtage 17 εpinal cord cDNA library and several full-length clones were obtained and sequenced. We amplified DNA fragmentε from chick C-Notch-1 gene by εimilar methodε (data not εhown) ; partial sequence data and pattern of expresεion indicate cloεe similarity to the rodent Notch-1 gene (Weinmaster et al., 1991, Development 113:199-205; 5 Weinmaεter et al., 1992, Development 116:931-941; Lardelli & Lendahl, 1993, Exp. Cell Res. 204:364-372) . Sequenceε were analyzed uεing the Wiεconεin GCG set of programs. The GenBank Acceεεion number for the Chick Delta-1 mRNA iε U26590. The DNA εequence of C-Del ta-1 correεpondε to a 10 protein of 722 amino acidε, structurally homologous to Drosophila Delta (Figs. 3, 4) and clearly diεtinct from vertebrate homologε of the Delta-related Serrate protein, which we have alεo cloned (data not εhown) . C-Delta-1 contains a putative transmembrane domain, a signal sequence 15 and 8 EGF-like repeats in its extracellular region (one repeat leεε than Drosophil a Delta) . The amino-terminal domain of C-Delta-1 iε cloεely related to a εimilar domain in the fly Delta protein, deεcribed aε neceεεary and sufficient for in vitro binding to Notch (Muskavitch, 1994, Dev. Biol. 20 166:415-430). Thiε conεerved region includeε the so-called DSL motif (Fig. 4) (Henderson et al. , 1994, Development 120:2913-2924; Tax et al., 1994, Nature 368:150-154), shared by all known memberε of the family of preεumed ligands of Notch-like proteinε (Delta and Serrate in Droεophila ; Lag-2 25 and Apx-1 in Caenorhabditis elegans ) (Henderεon et al. , 1994, Development 120:2913-2924; Tax et al., 1994, Nature 368:150-154; Fleming et al., 1990, Geneε Dev. 4:2188-2201; Thomaε et al. , 1991, Development 111:749-761; Mello et al. , 1994, Cell 77:95-106) . A εecond cyεteine-rich N-terminal 30 region iε conεerved between the fly and chick proteins, but abεent from the related C. elegans proteinε (Fig. 4) . The Xenopus Delta-1 homologue, X-Delta-1 which encodeε a protein that is 81% identical to C-Delta-1 and showε all the above structural motifs (Fig. 3) , has also been cloned. The 35 structural conservation between the chick and fly Delta proteinε, including domains identified as critical for Notch binding (Muskavitch, 1994, Dev. Biol. 166:415-430), suggestε that C-Delta-1 functions as a ligand for a chick Notch protein, and that a Delta/Notch-mediated mechanism of lateral inhibition might operate in the chick. 6.2. C-DELTA-1 AND C-NOTCH-1 EXPRESSION CORRELATES WITH ONSET OF NEUROGENESIS During Drosophila neurogenesis, Delta is tranεiently expressed in neural precursorε, inhibiting neighboring Notch-expressing cells from also becoming neural (Haenlin et al., 1990, Development 110:905-914; Kooh et al., 1993, Development 117:493-507). If c-Delta-1 acts similarly during chick neurogeneεis, it should also be transiently expresεed in neuronal precurεor cellε, while these are becoming determined. An analysis of C-Delta-1 expresεion in the developing CNS indicateε that this is indeed the case. In summary, whole ount in situ hybridization was performed. Formaldehyde fixed embryos were treated with protease and refixed with 4% formaldehyde/0.1% glutaraldehyde. Hybridization with DIG-labelled RNA probes was performed under stringent conditions (1.3xSSC, 50% formamide, 65 * C, pH5) in a buffer containing 0.2% Tween-20 and 0.5% CHAPS. Washed embryos were treated with Boehringer Blocking Reagent and incubated overnight in alkaline phosphataεe-coupled anti-DIG antibody. After extenεive washes, embryos were εtained from 3Omin to overnight. The embryo in Figure 5e waε wax-εectioned after hybridization. C-Delta-1 expreεεion in the neural plate iε firεt detected at εtage 6-7 (31h, 0/1 somite) , in scattered cells just anterior to the presomitic mesoderm (Fig. 5b , 5c) . This region gives rise to the mid/poεterior hindbrain, where the earlieεt differentiated CNS neurons are firεt detected by a neurofilament antibody at εtage 9 (3lh, 7-9 εomiteε) (Sechriεt & Bronner-Fraεer, 1991, Neuron 7:947-963), 6h after the initial C-Delta-1 expreεsion (Table 2) . TABLE 2 Hamburger-Hamilton Stage (nominal age in h; somite nos.) Neural tube Initial domains End final C-Delta-1 Initial NF S-phase expression expresεion Mid/posterior 4 6 9 Hindbrain (19h; 0) (24h; 0) (31h; 7-9) Spinal cord, 6 8 10 εomiteε 5-8 (24h; 0) (28h; 4-6) (36h; 10-12) Forebrain/ 7 8 10 Midbrain (25h; 1-3) (28h; 4-6) (36h; 10-12) Spinal cord, 8 9 11 εomiteε 9-12 (28h; 4-6) (31h; 7-9) (43h; 13-15) As neurogenesiε proceedε, expreεεion of C-Delta-1 continues to foreshadow the spatio-temporal pattern of neuronal differentiation (Table 2) , spreading poεteriorly along the εpinal cord and anteriorly into the midbrain and forebrain (Fig 5d, 5e) . For example, the most posterior expreεsing cells in the stage 8 spinal cord are at the level of the prospective 6th εomite, 6-8h before the first neurons at that level expresε neurofilament antigen (Sechrist & Bronner-Fraser, 1991, Neuron 7:947-963) (Table 2) . Table 2 εhows that the appearance of C-Delta-1 expression closely follows the withdrawal of the first neuronal precursorε from the diviεion cycle and precedes the appearance of neurofilament (NF) antigen in the resultant differentiating neurons. Mid-hindbrain comprises rhombomeres 4-6, the level of the otic primordium; posterior hindbrain includes rhombomeres 7 and 8, and somiteε 1-4. Data for the timing of withdrawal from cell-diviεion and for neurofilament expression are taken from Sechrist et al., 1991, Neuron 7:947-963. In all cases, C-Delta-1 is expressed in scattered cells within domains of uniform C-Notch-1 expreεεion (Fig. 5a). 6.3. LOCALIZATION AND TIME-COURSE EXPRESSION OF C-DELTA-1 The localization and time-course of C-Delta-1 expresεion indicate that the gene is εwitched on at an early εtep in neurogeneεiε, and that the cellε expreεsing C-Delta-1 are proεpective neuronε that have not yet begun to diεplay differentiation markerε. To teεt thiε hypotheεiε, we made uεe of the obεervationε of Sechrist and Bronner-Fraser (Sechriεt & Bronner-Fraεer, 1991, Neuron 7:947-963) that prospective neurons are the only non-cycling cellε in the early neural tube. They finiεh their final S phaεe ll-15h before expreεεing neurofilament antigen (Table 2) and their nuclei, after completing a laεt mitosis, adopt a characteristic location near the basal εurface of the neuroepithelium, where all the other cell nuclei are in S-phaεe (Sechriεt & Bronner-Fraεer, 1991, Neuron 7:947-963; Martin & Langman, 1965, J. Embryol. Exp. Morphol. 14:23-35) (Fig. 6a) . We labelled stage 7-9 embryos with bromodeoxyuridine (BrdU) , and double-stained for BrdU incorporation and C-Delta-1 expression. 95% of the C-Delta-1-expressing cellε were unlabelled, with their nuclei predominantly located near the basal surface, where most other nuclei were BrdU-labelied (Fig. 6b , 6c) . 75μl O.lmM BrdU in PBS was dropped onto stage 7-9 embryos which were incubated at 38"C for 2-4h before fixation for in εitu hybridization. 15μm cryoεtat sectionε were hybridized with DIG-labelled RNA probeε, eεεentially according to the method of Strahle et al. (Strahle et al., 1994, Trendε In Genet. Sci. 10:75-76). After εtaining, slides were washed in PBS, and procesεed for BrdU immunodetection (Biffo et al., 1992, Hiεtochem. Cytochem. 40:535-540). Anti-BrdU (1:1000; Sigma) waε detected using FITC-coupled goat anti-mouse secondary antibody (Cappel) . C-Delta-1 expresεion waε examined by DIC microεcopy, and BrdU-labelling by conventional and confocal fluoreεcence microscopy. These results imply that C-Delta-1 is expresεed in cells that have withdrawn from the cell cycle and must indeed be prospective neurons. The few BrdU C- Delta-1 * cells have their nuclei outside the basal zone; these may be cellε that finished their final S-phase soon after exposure to BrdU, moved apically to complete their final mitosis, and switched on C-Delta-1 expresεion. C-Delta-1 iε alεo expreεsed in the later neural tube and peripheral nervouε εyεtem. Again, the timing of expreεεion and the location of the expreεεing cellε imply that they are neuronal precurεorε that have not yet begun to differentiate (data not εhown). Thuε, C-Delta-1 expreεsion appears to be the earliest known marker for prospective neuronε. In addition, the tranεcription pattern of both C-Delta-1 and C-Serrate-1 overlap that of C-Notch-1 in many regionε of the embryo (data not εhown) which εuggeεt that C-Notch-1, like Notch in Droεophila , iε a receptor for both proteinε. In particular, all three geneε are expressed in the neurogenic region of the developing central nervous εystem, and here a striking relationship is εeen: the expreεεion of both C-Serrate-l and C-Delta-1 is confined to the domain of C-Notch-l expreεεion; but within thiε domain, the regionε of C-Serrate-1 and C-Delta-1 are preciεely complementary. The overlapping expression patterns suggeεt conservation of their functional relationship with Notch and imply that development of the chick and in particular the central nervous syεtem involves the concerted interaction of C-Notch-l with different ligands at different locationε. 6.4. DISCUSSION The Xenopus homolog of C-Delta-1 has been cloned in a similar manner. In brief, a PCR fragment of X-Delta-1 was isolated and εequenced. Thiε fragment waε then uεed to identify the full length clone of X-Delta-1. The X-Delta-1 expression pattern was studied. It was shown that X-Delta-1 is expreεεed in εcattered cellε in the domain of the neural plate where primary neuronal precurεorε are being generated, εuggesting that the cells expressing X-Delta-1 are the prospective primary neurons. In addition, X-Delta-1 is alεo expreεεed at other εites and times of neurogenesis, including the anterior neural plate and neurogenic placodes and later stages of neural tube development when secondary neurons are generated. Ectopic X-Delta-1 activity inhibited production of primary neurons; interference with endogenous X-Delta-1 activity resulted in overproduction of primary neurons. Theεe reεultε εhow that X-Delta-l mediateε lateral inhibition delivered by proεpective neuronε to adjacent cells. It was shown that ectopic expreεsion of X-Delta-l in Xenopus eggs suppresses primary neurogenesis, and that ectopic expresεion of a truncated X-Delta-l protein which retainε only two amino acidε of the cytoplasmic domain interferes with endogenous signalling and leads to extra cells developing aε neuronal precursorε. (Chitnis et al., Nature (in presε). Preliminary evidence indicates that C-Del ta-1 has a similar inhibitory action when expresεed in Xenopus embryoε (data not εhown) . We propoεe that C-Delta-1 , like itε Drosophila and Xenopus counterpartε, mediateε lateral inhibition throughout neurogeneεiε to reεtrict the proportion of cells that, at any time, become committed to a neural fate. C-Delta-1 iε generally expressed during neurogenesis in many other sites, in both the CNS and PNS, and, for example, the developing ear. It has been shown in the CNS that C-Notch is expressed in the ventricular zone of the E5 chick hindbrain, in dividing cells adjacent to the lumen of the neural tube. C-Delta-1 is expresεed in the adjacent layer of cellε, which have εtopped dividing and are becoming committed aε neuronal precursor cells. Thuε, Delta/Notch signalling could act here, as in other neural tisεueε, to maintain a population of uncommitted cycling neuronal εtem cells. 7. ISOLATION AND CHARACTERIZATION OF A MOUSE DELTA HOMOLOG A mouse Delta homolog, termed M-Delta-l, waε isolated as follows: Mouse Del ta-1 gene Tiεsue Origin: 8.5 and 9.5-day mouse embryonic RNA Isolation Method: a) random primed cDNA against above RNA b) PCR of above cDNA using PCR primer 1: GGITTCACITGGCCIGGIACNTT (SEQ ID NO:23) [encoding GFTWPGTF (SEQ ID NO:24), a region which is εpecific for Delta-, not Serrate- like proteinε] PCR primer 2 : GTICCICC(G/A)TT(C/T)T (G/A) CAIGG(G/A)TT (SEQ ID NO:25) [encoding NPCKNGGT (SEQ ID NO:26), a sequence preεent in many of the EGF-like repeatε] Amplification conditionε: 50 ng cDNA, 1 μg each primer, 0.2 mM dNTP'ε, 1.8 U Taq (Perkin- Elmer) in 50 μl of εupplied buffer. 40 cycleε of: 94°C/30 sec, 45°C/2 min, 72°C/1 min extended by 2 sec each cycle. The amplified fragment was an approximately 650 baεe pair fragment which was partially sequenced to determine its relationεhip to C-Delta-1 . c) a mouεe 11.5 day cDNA library (Clontech) waε screened. Of several positive clones, one (pMDL2 ; inεert εize approximately 4 kb) included the complete protein-coding region whose DNA εequence waε completely determined. Figure 7 (SEQ ID NO:11) εhowε the nucleotide sequence of the isolated clone containing M-Delta-l DNA. Figure 8 (SEQ ID NO:12) shows the predicted amino acid sequence of M-Delta-l. Figure 9 showε and amino acid alignment of the predicted amino acid εequenceε for M-Delta-l and C-Delta-1. Identical amino acidε are boxed εhowing the extensive sequence homology. The consensuε εequence is shown below (SEQ ID NO: 13) . Expression pattern: The expresεion pattern was determined to be esεentially the same as that observed for C-Delta-1, in particular, in the preεomitic meεoderm, central nervouε εystem, peripheral nervous syεtem, and kidney. 8. ISOLATION AND CHARACTERIZATION OF A HUMAN DELTA HOMOLOG A human Delta-1 homolog, termed H-Delta-1 (HDI) , waε isolated as follows: A human genomic library with inserts ranging in size from 100-150 kb was probed with an EcoRI fragment of the mouse Delta-1 (M-Delta-l) gene. From the library a genomic human PAC clone waε iεolated which hybridized to the EcoRI fragment. Next, two degenerate oligonucleotideε were uεed to amplify by PCR a fragment of the genomic human PAC clone. The degenerate oligoε were: 5' ACIATGAA(C/T)AA(C/T)CTIGCIAA(C/T)TG (SEQ ID NO:27) [encoding TMNNLANC (SEQ ID NO:28)] and 3' AC(A/G)TAIACIGA(C/T)TG(A/G)TA(C/T)TTIGT (SEQ ID NO:29) [encoding TKYQSVYV (SEQ ID NO:30) or 3 ' GC(A/G/T)ATIAC(A/G)CA(C/T)TC(A/G)TC(C/T)TT(C/T)TC (SEQ ID NO:31) [encoding EKDECVIA (SEQ ID NO:32). On the basiε of the cDNA εequenceε for chicken and mouεe Delta-1, it waε expected that fragmentε of approximately 354 and 387 base pairs would be iεolated, using the 5' and the two different 3' oligos, respectively. in fact, however, two εingle iεolates of 525 base pairs and another that was 30 base pairs εmaller, aε expected, were obtained. The larger iεolate waε εequenced by dideoxy εequencing. The nucleotide εequence iε εhown in Figure 10 (SEQ ID NO:14). Alεo εhown in Figure 10 are the predicted amino acid sequences of the amplified DNA fragment (SEQ ID NOS:15, 16, 17) for the three different readings frames. Due to sequencing errors, the full uninterrupted sequence between both primers was not identified. Aε a conεequence, one cannot predict the amino acid εequence directly from the DNA εequence obtained. However, Figure 11 εhowε the amino acid sequence homology between human Delta-1 (top line) (SEQ ID NO:18) and chick Delta-1 (bottom line) as determined by eye. Because of the sequencing errors, the homology was obtained by εwitching amongεt the three different reading frameε to identify the homologouε regionε. Using the larger isolate (SEQ ID NO:14) as probe, a human fetal brain plasmid library (Clontech) was εcreened in an attempt to iεolate full-length H-Delta-1 (HDI) genes. This yielded four poεitive plaques. Two of these positiveε (HD13 and HD124) εurvived reεcreening and reacted positively with a large human genomic fragment on a Southern Blot. These poεitive cloneε were εubcloned by digeεting with EcoRI and ligating the fragments into a Blueεcript KS " vector. The nucleotide εequences of the inserts were obtained by dideoxy sequencing using T3 and T7 primers. The results showed that HD124 waε homologous to chicken Delta-1 at both ends; however, one end of HD13 showed no homology. Restriction digeεtionε with a panel of enzymeε εhowed very εimilar patternε between the two cloneε, each of which had an inεert of about 2 kb, but with differenceε at the 3' end of HD13. HD13 and HD124 were cut with BstXl, Xbal , Hindlll and Xhol and the reεtriction fragmentε were inεerted into Bluescript KS " , and then εequenced aε deεcribed above to obtain internal εequence. The εequence that waε obtained repreεentε the 3' about 2000 baεes of HDI, extending into the 3' non-coding region. HD13 is contained within HD124; however, the added sequence at the 5' end of HD13 is likely due to a cloning artifact. Since the sequence thus obtained did not contain the 5' end of HDI, HD124 was used as a probe for subsequent hybridizations in a T cell library and in another fetal brain library (Lambda-Zap, Stratagene) . A screen of the T cell library resulted in no poεitives. However, screening the Lambda-Zap library reεulted in two positive clones, HD113 and HD118. Theεe clones were inserted into a Blueεcript KS " vector uεing .EcoRI as deεcribed above. The inεertε were digeεted with a panel of restriction enzymeε for compariεon with HD13 and HD124, and the 5' and 3' endε were εequenced uεing T3 and T7 primerε. HD113 waε determined to be only a εmall piece of cDNA that when εequenced showed no homology to any known Delta. However, HD118 was 3 kb in length, and included the entire εequence of HD124 with additional 5' εequenceε. A εet of clones were iεolated uεing neεted deletionε from HD118; theεe cloneε were then subjected to dideoxy sequencing using an automated sequencer. Figure 12A presents the partial nucleotide contig sequence (SEQ ID NO:33) of human Delta obtained from clone HD118. Due to sequencing errors, the full uninterrupted nucleotide sequence of human Delta was not determined. Figure 12B shows the partial nucleotide contig sequence (SEQ ID NO:33) of human Delta (top line) , with the predicted amino acid sequence in three different reading frames presented below, the second line being reading frame 1 (SEQ ID NO: 34), the third line being reading frame 2 (SEQ ID NO:35), and the fourth line being reading frame 3 (SEQ ID NO:36). Sequence homology was determined by eye using the mouse Delta-1 amino acid εequence. The sequences with the greatest degree of homology to the mouεe amino acid εequence are boxed in Figure 12B, and represent the predicted amino acid sequence of human Delta-1. The composite reεulting amino acid εequence iε εhown in Figure 14. (In Figure 14, the various uninterrupted portions of the human Delta sequence are assigned respectively, SEQ ID NOS:39 through 65.) Note that due to sequencing errors, the reading frame with the greatest homology is not the εame throughout the εequence and εhiftε at poεitionε where there are errorε in the sequence. Further, the homology determined by eye to chicken and mouse Delta indicates that the amino acid sequence deduced from the determined human Delta nucleotide sequence containε all but about the N-terminal 100-150 amino acids of human Delta-1. Figure 13 presentε the nucleotide εequence of mouεe Delta-1 (top line, SEQ ID NO:37) and the contig nucleotide εequence of human Deita-l as depicted in Figures 12A and 12B (second line, SEQ ID NO:33) and the nucleotide consensuε εequence between mouεe and human Delta (third line, SEQ ID NO:38) . Using probes containing the human Delta 5' nucleotide sequences presented in Figure 12A, cDNA librarieε are probed to iεolate the 5' end of the human Delta gene. Primary positive clones are obtained and then confirmed as secondary positives. The secondary positives are purified and grown further. The DNA is then isolated and subcloned for sequencing. The present invention is not to be limited in scope by the specific embodimentε deεcribed herein. Indeed, variouε modificationε of the invention in addition to thoεe deεcribed herein will become apparent to thoεe εkilled in the art from the foregoing deεcription and accompanying figures. Such modifications are intended to fall within the scope of the appended claims. Variouε references are cited herein, the discloεureε of which are incorporated by reference in their entiretieε.

Claims: WHAT IS CLAIMED IS: 1. A purified vertebrate Delta protein. 2. The protein of claim 1 which is a human protein. 3. The protein of claim 1 which is a mammalian protein, 4. The protein of claim 1 which comprises the amino acid sequence substantially as εet forth in amino acid numbers 1-722 of SEQ ID NO: 12. 5. A purified derivative or analog of the protein of claim 1, which is able to diεplay one or more functional , activitieε of a Delta protein. 6. A purified derivative or analog of the protein cf claim 2, which iε able to display one or more functional activities of a human or D. melanogaster Delta protein. 7. The derivative or analog of claim 5 which is able to be bound by an antibody directed againεt a human or D . melanogaster Delta protein. 8. A purified fragment of the protein of claim 2, which iε able to be bound by an antibody directed againεt a human Delta protein. 9. A molecule compriεing the fragment of claim 8. 10. A purified fragment of the protein of claim 2 which iε able to diεplay one or more functional activities of a human Delta protein. 11. A purified fragment of a vertebrate Delta protein compriεing a domain of the protein selected from the group consisting of the extracellular domain, DSL domain, domain amino-terminal to the DSL domain, epidermal growth factor-like repeat domain, transmembrane domain, and intracellular domain. 12. A purified fragment of a Delta protein comprising the membrane-asεociated region of the protein. 13. A purified fragment of a Delta protein compriεing an epidermal growth factor-homologouε repeat of the protein. 14. The fragment of claim 11 in which the Delta protein iε a human Delta protein. 15. A purified fragment of a vertebrate Delta protein compriεing a region homologouε co a Notch protein or a Delta protein, and conεiεting of at least six amino acidε. 16. A purified fragment of a vertebrate Delta protein comprising the region of the protein with the greatest homology over an identical number of amino acids to amino acid numbers 1-722 as εhown in Figure 8 (SEQ ID NO: 12). 17. A chimeric protein compriεing a fragment of a vertebrate Delta protein consisting of at least 20 amino acids fuεed via a covalent bond to an amino acid sequence of a εecond protein, in which the εecond protein iε not the Delta protein. 18. The chimeric protein of claim 17 in which the fragment of a vertebrate Delta protein iε a fragment capable of being bound by an anti-Delta antibody. 19. The chimeric protein of claim 18 in which the Delta protein iε a human protein. 20. The chimeric protein of claim 19 which is able to display one or more functional activities of a Delta protein. 21. A purified fragment of a vertebrate Delta protein which (a) is capable of being bound by an anti-Delta antibody; and (b) lacks the transmembrane and intracellular domains of the protein. 22. A purified fragment of a vertebrate Delta protein which (a) is capable of being bound by an anti-Delta antibody; and (b) lacks the extracellular domain of the protein. 23. A purified fragment of a vertebrate Delta protein which is able to bind to a Notch protein. 24. The fragment of claim 23, which lacks the epidermal growth factor-like repeats of the Delta protein. 25. The fragment of claim 23 in which the Delta protein is a human Delta protein. 26. The fragment of claim 23, which is a fragment of SEQ ID NO:18. 27. A molecule comprising the fragment of claim 23. 28. The fragment of claim 11 or 21 in which the Delta protein is a human Delta protein. 29. An antibody which is capable of binding the Delta protein of claim 1, and which does not bind to a Droεophila Delta protein. 30. An antibody which is capable of binding the Delta protein of claim 2, and which does not bind to a Droεophila Delta protein. 31. The antibody of claim 1 which is monoclonal. 32. A molecule comprising a fragment of the antibody of claim 31, which fragment is capable of binding a Delta protein. 33. An isolated nucleic acid comprising a nucleotide εequence encoding a vertebrate Delta protein. 34. The nucleic acid of claim 33 which iε DNA. 35. An isolated nucleic acid comprising a nucleotide sequence complementary to the nucleotide εequence of claim 33. 36. An iεolated nucleic acid compriεing a nucleotide εequence encoding the Delta protein of claim 2. 37. An iεolated nucleic acid compriεing a fragment of a vertebrate Delta gene consisting of at least 50 nucleotideε. 38. An iεolated nucleic acid compriεing a nucleotide sequence encoding the fragment of claim 10. 39. An isolated nucleic acid compriεing a nucleotide εequence encoding the fragment of claim 11. 40. An isolated nucleic acid compriεing a nucleotide sequence encoding the fragment of claim 23. 41. An isolated nucleic acid comprising a nucleotide sequence encoding a protein, said protein compriεing amino acid numbers 1-175 of the human Delta sequence depicted in Figure 11 (SEQ ID NO: 18). 42. An iεolated nucleic acid comprising a nucleotide sequence encoding the protein of claim 17. 43. A recombinant cell containing the nucleic acid of claim 33. 44. A recombinant cell containing the nucleic acid of claim 39. 45. A recombinant cell containing the nucleic acid of claim 41. 46. A method of producing a vertebrate Delta protein compriεing growing a recombinant cell containing the nucleic acid of claim 33 such that the encoded vertebrate Delta protein is expresεed by the cell, and recovering the expreεεed Delta protein. 47. A method of producing a vertebrate Delta protein comprising growing a recombinant cell containing the nucleic acid of claim 41 εuch that the encoded Delta protein iε expreεεed by the cell, and recovering the expreεεed Delta protein. 48. A method of producing a protein compriεing a fragment of a vertebrate Delta protein, which method compriεes growing a recombinant cell containing the nucleic acid of claim 39 such that the encoded protein is expreεεed by the cell, and recovering the expreεεed protein. 49. The product of the proceεε of claim 46. 50. The product of the proceεε of claim 47. 51. The product of the proceεε of claim 48. 52. A pharmaceutical compoεition comprising a therapeutically effective amount of a Delta protein; and a pharmaceutically acceptable carrier. 53. The compoεition of claim 52 in which the Delta protein is a human Delta protein. 54. A pharmaceutical composition compriεing a therapeutically effective amount of the fragment of claim 11; and a pharmaceutically acceptable carrier. 55. A pharmaceutical compoεition compriεing a therapeutically effective amount of the fragment of claim 23; and a pharmaceutically acceptable carrier. 56. A pharmaceutical compoεition comprising a therapeutically effective amount of a derivative or analog of a Delta protein, which derivative or analog is characterized by the ability to bind to a Notch protein or to a molecule comprising the epidermal growth factor-like repeats 11 and 12 of a Notch protein; and a pharmaceutically acceptable carrier. 57. A pharmaceutical composition comprising a therapeutically effective amount of the nucleic acid of claim 33; and a pharmaceutically acceptable carrier. 58. A pharmaceutical composition comprising a therapeutically effective amount of the nucleic acid of claim 35; and a pharmaceutically acceptable carrier. 59. A pharmaceutical compoεition compriεing a therapeutically effective amount of the nucleic acid of claim 39; and a pharmaceutically acceptable carrier. 60. A pharmaceutical composition comprising a therapeutically effective amount of an antibody which bindε to a Delta protein; and a pharmaceutically acceptable carrier. 61. A pharmaceutical composition compriεing a therapeutically effective amount cf a fragment or derivative of an antibody to a Delta protein containing the binding domain of the antibody; and a pharmaceutically acceptable carrier. 62. A method of treating or preventing a diεease or diεorder in a εubject compriεing administering to a εubject in which εuch treatment or prevention is desired a therapeutically effective amount of a Delta protein or derivative thereof which is able to bind to a Notch protein. 63. The method according to claim 62 in which the diεeaεe or disorder iε a malignancy characterized by increaεed Notch activity or increaεed expression of a Notch protein or of a Notch derivative capable of being bound by an anti-Notch antibody, relative to said Notch activity or expression in an analogous non-malignant εample. 64. The method according to claim 62 in which the diεeaεe or disorder iε εelected from the group conεisting of cervical cancer, breast cancer, colon cancer, melanoma, εeminoma, and lung cancer. 65. The method according to claim 62 in which the subject is a human. 66. A method of treating or preventing a diεeaεe or diεorder in a εubject compriεing adminiεtering to a εubject in which εuch treatment or prevention is desired a therapeutically effective amount of a molecule, in which the molecule is an oligonucleotide which (a) consiεtε of at least εix nucleotideε; (b) compriεes a sequence complementary to at least a portion of an RNA transcript of a Delta gene; and (c) is hybridizable to the RNA transcript. 67. A method of treating or preventing a diεeaεe or diεorder in a εubject compriεing adminiεtering to a subject in which such treatment or prevention iε deεired an effective amount of the nucleic acid of claim 33 or 39. 68. A method of treating or preventing a diεeaεe or diεorder in a subject comprising administering to a subject in which such treatment or prevention is deεired an effective amount of the antibody of claim 30. 69. The method according to claim 52 in which the diseaεe or disorder is a disease or disorder cf the central nervous system. 70. An iεolated oligonucleotide conεiεting of at leaεt six nucleotides, and compriεing a εequence complementary to at leaεt a portion of an RNA tranεcript of a Delta gene, which oligonucleotide iε hybridizable to the RNA tranεcript. 71. A pharmaceutical compoεition compriεing the oligonucleotide of claim 70; and a pharmaceutically acceptable carrier. 72. A method of inhibiting the expreεsion of a nucleic acid sequence encoding a Delta protein in a cell comprising providing the cell with an effective amount of the oligonucleotide of claim 70. 73. A method of diagnosing a disease or disorder characterized by an aberrant level of Notch-Delta protein binding activity in a patient, comprising measuring the ability of a Notch protein in a sample derived from the patient to bind to a Delta protein, in which an increase or decrease in the ability of the Notcn protein to bind to the Delta protein, relative to the ability found in an analogous sample from a normal individual, indicates the presence of the disease or disorder in the patient. 74. A method of diagnoεing a diεeaεe or disorder characterized by an aberrant level of Delta protein in a patient, comprising measuring the level of Delta protein in a sample derived from the patient, in which an increase or decrease in the level of Delta protein, relative to the level of Delta protein found in an analogous sample from a normal individual, indicateε the presence of the diεeaεe or disorder in the patient. 75. A purified human protein which iε encoded by a firεt nucleic acid that is hybridizable to a second nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said sequence. 76. The fragment of claim 8 which is encoded by a first nucleic acid that is hybridizable to a second nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said εequence. 77. The fragment of claim 10 which iε encoded by a firεt nucleic acid that iε hybridizable to a second nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at leaεt 50 nucleotide portion of said sequence. 78. The fragment of claim 14 which iε encoded by a firεt nucleic acid that iε hybridizable to a εecond nucleic acid having the nucleotide εequence depicted in Figure 12A (SEQ ID NO: 33) or having an at least 50 nucleotide portion of said εequence. 79. The fragment of claim 25 which is encoded by a first nucleic acid that is hybridizable to a second nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at leaεt 50 nucleotide portion of said εequence. 80. The fragment of claim 10 or 25, which iε a fragment of SEQ ID NO:39. 81. The fragment of claim 28 which iε encoded by a firεt nucleic acid that iε hybridizable tc a εecond nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said εequence. 82. An isolated nucleic acid comprising the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33). 83. An isolated nucleic acid comprising a nucleotide εequence complementary to the nucleotide εequence depicted in Figure 12A (SEQ ID NO:33) . 84. A purified protein compriεing at leaεt a portion of a human Delta amino acid εequence, εaid portion εelected from the group conεiεting of amino acid numberε 1- 192 depicted in Figure 14 (SEQ ID NO:39) , amino acid numberε 205-213 depicted in Figure 14 (SEQ ID NO:43), amino acid numberε 214-370 depicted in Figure 14 (SEQ ID NO:44), amino acid numberε 371-382 depicted in Figure 14 (SEQ ID NO:45), amino acid numberε 394-418 depicted in Figure 14 (SEQ ID NO:49), amino acid numberε 419-428 depicted in Figure 14 (SEQ ID NO:50), amino acid numbers 443-458 depicted in Figure 14 (SEQ ID NO:52) , amino acid numbers 459-469 depicted in Figure 14 (SEQ ID NO:53), amino acid numbers 470-495 depicted in Figure 14 (SEQ ID NO:54), amino acid numbers 496-508 depicted in Figure 14 (SEQ ID NO:55), and amino acid numbers 516-519 depicted in Figure 14 (SEQ ID NO:59). 85. The protein of claim 84 which is encoded by a first nucleic acid that is hybridizable to a second nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said εequence. 86. A purified protein which iε encoded by a first nucleic acid hybridizable under stringent conditions to a second nucleic acid having a nucleotide sequence comprising a sequence selected from the group consisting of nucleotide numbers 60-634 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 746-772 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 775-1245 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1249-1284 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1415-1489 depicted in Figure 12B (SEQ ID NO:33) , nucleotide numbers 1493-1522 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1526-1567 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1570-1618 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1622-1653 depicted in Figure 12B (SEQ ID NO:33), nucleotide numbers 1658-1735 depicted in Figure 12B (SEQ ID NO:33), and nucleotide numbers 1739-1777 depicted in Figure 12B (SEQ ID NO:33). 87. The protein of claim 2 which compriseε a portion of the human Delta amino acid sequence set forth in Figure 14, said portion selected from the group consiεting of amino acid numberε 1-192 (SEQ ID NO:39) , amino acid numberε 205-213 14 (SEQ ID NO:43), amino acid numberε 214-370 (SEQ ID NO:44), amino acid numberε 371-382 (SEQ ID NO:45), amino acid numberε 394-418 (SEQ ID NO:49), amino acid numbers 419-428 (SEQ ID NO:50), amino acid numbers 443-458 (SEQ ID NO:52), amino acid numbers 459-469 (SEQ ID NO:53), amino acid numbers 470-495 (SEQ ID NO:54), amino acid numberε 496-508 (SEQ ID NO:55), and amino acid numberε 516-519 (SEQ ID NO:59). 88. The protein of claim 75 in which the first nucleic acid is hybridizable to the second nucleic acid under conditions of high εtringency. 89. The fragment of claim 76, 77 or 78 in which the first nucleic acid is hybridizable to the second nucleic acid under conditions of high stringency. 90. An isolated nucleic acid hybridizable under conditions of high stringency to a nucleic acid having the nucleotide εequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said sequence. 91. The nucleic acid of claim 90 which comprises a cDNA sequence hybridizable under conditions of high stringency to a nucleic acid having the nucleotide sequence depicted in Figure 12A (SEQ ID NO:33) or having an at least 50 nucleotide portion of said sequence. 92. An isolated nucleic acid comprising a nucleotide εequence complementary to a cDNA εequence hybridizable under conditionε of high εtringency to a nucleic acid having the nucleotide εequence depicted in Figure 12A (SEQ ID NO:33) or having an at leaεt 50 nucleotide portion of said sequence. 93. A purified human protein which iε encoded by a firεt nucleic acid that iε hybridizable to a εecond nucleic acid having the nucleotide εequence depicted in Figure 10 (SEQ ID NO:14) or having an at least 50 nucleotide portion of said sequence. 94. The fragment of claim 8 which iε encoded by a first nucleic acid that iε hybridizable to a εecond nucleic acid having the nucleotide εequence depicted in Figure 10 (SEQ ID NO:14) or having an at leaεt 50 nucleotide portion of said sequence. 95. An iεolated nucleic acid hybridizable under conditionε of high εtringency to a nucleic acid having the nucleotide εequence depicted in Figure 10 (SEQ ID NO:14) or having an at leaεt 50 nucleotide portion of εaid εequence. 96. An iεolated nucleic acid hybridizable under conditionε of high εtringency to a nucleic acid having the consensus nucleotide sequence depicted in Figure 13 (SEQ ID NO:38) or having an at leaεt 50 nucleotide portion of εaid εequence. 97. A purified protein encoded by a first nucleic acid hybridizable to a εecond nucleic acid having the consenεus nucleotide sequence depicted in Figure 13 (SEQ ID NO:38) or having an at least 50 nucleotide portion of said sequence. 98. An isolated nucleic acid comprising a nucleotide sequence that is complementary to the nucleotide sequence of the nucleic acid of claim 92 or 96.

Inventors: ARTAVANIS-TSAKONAS SPYRIDON, GRAY GRACE E, HENRIQUE DOMINGO M P, ISH-HOROWICZ DAVID, LEWIS JULIAN H, ARTAVANIS-TSAKONAS, SPYRIDON, GRAY, GRACE, E., HENRIQUE, DOMINGO, M., P., ISH-HOROWICZ, DAVID, LEWIS, JULIAN, H.
Applicants: ARTAVANIS TSAKONAS SPYRIDON, GRAY GRACE E, HENRIQUE DOMINGO M P, IMP CANCER RES TECH, ISH HOROWICZ DAVID, LEWIS JULIAN H, UNIV YALE, ARTAVANIS-TSAKONAS, SPYRIDON, GRAY, GRACE, E., HENRIQUE, DOMINGO, M., P., IMPERIAL CANCER RESEARCH TECHNOLOGY, LTD., ISH-HOROWICZ, DAVID, LEWIS, JULIAN, H., YALE UNIVERSITY
Application year: 1996
Main classification: C07H17
IPC codes: A61K31, A61K38, A61K39, A61K48, A61P25, A61P35, C07K14, C07K16, C12N5, C12N15, C12P21, C12R1