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Human Brain Development

$305
50 tests
100 µl
This Cell Signaling Technology antibody is conjugated to phycoerythrin (PE) and tested in-house for direct flow cytometric analysis in human cells. This antibody is expected to exhibit the same species cross-reactivity as the unconjugated EOMES (D8D1R) Rabbit mAb #81493.
APPLICATIONS
REACTIVITY
Human

Application Methods: Flow Cytometry

Background: The T-box family of transcription factors is named for their shared homology with the DNA binding domain of the mouse brachyury (T) gene product. Members of this family bind DNA and are capable of transcriptional activation. They also have evolutionarily conserved expression patterns and roles in embryonic development, primarily mesoderm development (1). EOMES, or Tbr2 (T-box brain 2), is a master regulator of mesoderm formation that is also essential for trophoblast formation, gastrulation, neurogenesis and the differentiation of certain T cell subsets. Embryos from EOMES knock-out mice die soon after implantation due to their inability to develop a trophoblast (2,3). Conditional neural knock out mice show defects in development of a specific population of neural progenators known as Intermediate Progenator Cells (IPCs) that give rise only to neurons (4,5). These cells are formed from the radial glia in the ventricular and sub-ventricular zones of the cortex. Expression of EOMES increases as cells develop from radial glia to IPCs and then decreases as IPCs progress to neurons. Recent evidence suggests that EOMES and IPCs may also play a role neurogenesis in the adult hippocampal SGZ (5). EOMES is also a key transcription factor for memory T cells and for full effector differentiation of CD8+ T cells (6). Expression of EOMES is induced in CD8+ T cells following viral infection and bacterial infection where sufficient IL-12 has been produced to elicit acute host cell response (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Flow Cytometry, Immunofluorescence (Immunocytochemistry), Western Blotting

Background: The T-box family of transcription factors is named for their shared homology with the DNA binding domain of the mouse brachyury (T) gene product. Members of this family bind DNA and are capable of transcriptional activation. They also have evolutionarily conserved expression patterns and roles in embryonic development, primarily mesoderm development (1). EOMES, or Tbr2 (T-box brain 2), is a master regulator of mesoderm formation that is also essential for trophoblast formation, gastrulation, neurogenesis and the differentiation of certain T cell subsets. Embryos from EOMES knock-out mice die soon after implantation due to their inability to develop a trophoblast (2,3). Conditional neural knock out mice show defects in development of a specific population of neural progenators known as Intermediate Progenator Cells (IPCs) that give rise only to neurons (4,5). These cells are formed from the radial glia in the ventricular and sub-ventricular zones of the cortex. Expression of EOMES increases as cells develop from radial glia to IPCs and then decreases as IPCs progress to neurons. Recent evidence suggests that EOMES and IPCs may also play a role neurogenesis in the adult hippocampal SGZ (5). EOMES is also a key transcription factor for memory T cells and for full effector differentiation of CD8+ T cells (6). Expression of EOMES is induced in CD8+ T cells following viral infection and bacterial infection where sufficient IL-12 has been produced to elicit acute host cell response (7).

$305
50 tests
100 µl
This Cell Signaling Technology antibody is conjugated to Alexa Fluor® 647 fluorescent dye and tested in-house for direct flow cytometric analysis in human cells. This antibody is expected to exhibit the same species cross-reactivity as the unconjugated EOMES (D8D1R) Rabbit mAb #81493.
APPLICATIONS
REACTIVITY
Human

Application Methods: Flow Cytometry

Background: The T-box family of transcription factors is named for their shared homology with the DNA binding domain of the mouse brachyury (T) gene product. Members of this family bind DNA and are capable of transcriptional activation. They also have evolutionarily conserved expression patterns and roles in embryonic development, primarily mesoderm development (1). EOMES, or Tbr2 (T-box brain 2), is a master regulator of mesoderm formation that is also essential for trophoblast formation, gastrulation, neurogenesis and the differentiation of certain T cell subsets. Embryos from EOMES knock-out mice die soon after implantation due to their inability to develop a trophoblast (2,3). Conditional neural knock out mice show defects in development of a specific population of neural progenators known as Intermediate Progenator Cells (IPCs) that give rise only to neurons (4,5). These cells are formed from the radial glia in the ventricular and sub-ventricular zones of the cortex. Expression of EOMES increases as cells develop from radial glia to IPCs and then decreases as IPCs progress to neurons. Recent evidence suggests that EOMES and IPCs may also play a role neurogenesis in the adult hippocampal SGZ (5). EOMES is also a key transcription factor for memory T cells and for full effector differentiation of CD8+ T cells (6). Expression of EOMES is induced in CD8+ T cells following viral infection and bacterial infection where sufficient IL-12 has been produced to elicit acute host cell response (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunoprecipitation, Western Blotting

Background: The T-box family of transcription factors is named for their shared homology with the DNA binding domain of the mouse brachyury (T) gene product. Members of this family bind DNA and are capable of transcriptional activation. They also have evolutionarily conserved expression patterns and roles in embryonic development, primarily mesoderm development (1). EOMES, or Tbr2 (T-box brain 2), is a master regulator of mesoderm formation that is also essential for trophoblast formation, gastrulation, neurogenesis and the differentiation of certain T cell subsets. Embryos from EOMES knock-out mice die soon after implantation due to their inability to develop a trophoblast (2,3). Conditional neural knock out mice show defects in development of a specific population of neural progenators known as Intermediate Progenator Cells (IPCs) that give rise only to neurons (4,5). These cells are formed from the radial glia in the ventricular and sub-ventricular zones of the cortex. Expression of EOMES increases as cells develop from radial glia to IPCs and then decreases as IPCs progress to neurons. Recent evidence suggests that EOMES and IPCs may also play a role neurogenesis in the adult hippocampal SGZ (5). EOMES is also a key transcription factor for memory T cells and for full effector differentiation of CD8+ T cells (6). Expression of EOMES is induced in CD8+ T cells following viral infection and bacterial infection where sufficient IL-12 has been produced to elicit acute host cell response (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunofluorescence (Frozen), Immunohistochemistry (Paraffin)

Background: T-box, brain, 1 (TBR1) is a transcription factor important in vertebrate embryo development. As a member of T-Box family of transcription factors, TBR1 is expressed in postmitotic glutamatergic projection neurons (1). During cortical neurogenesis, sequential expression of transcription factors Pax6, TBR2, and TBR1 regulates discrete steps in projection neuron differentiation (2). TBR1 is enriched in layer 6 of the developing cortex. In the absence of TBR1, TBR1 mutants exhibit profound defects in frontal cortex and layer 6 differentiation, suggesting that TBR1 regulates regional and laminar identity of postmitotic cortical neurons (3). Therefore, TBR1 expression can be used as a marker for postmitotic glutamatergic neurons and cortical laminar specificity.

$260
100 µl
REACTIVITY
Human

Background: The T-box family of transcription factors is named for their shared homology with the DNA binding domain of the mouse brachyury (T) gene product. Members of this family bind DNA and are capable of transcriptional activation. They also have evolutionarily conserved expression patterns and roles in embryonic development, primarily mesoderm development (1). EOMES, or Tbr2 (T-box brain 2), is a master regulator of mesoderm formation that is also essential for trophoblast formation, gastrulation, neurogenesis and the differentiation of certain T cell subsets. Embryos from EOMES knock-out mice die soon after implantation due to their inability to develop a trophoblast (2,3). Conditional neural knock out mice show defects in development of a specific population of neural progenators known as Intermediate Progenator Cells (IPCs) that give rise only to neurons (4,5). These cells are formed from the radial glia in the ventricular and sub-ventricular zones of the cortex. Expression of EOMES increases as cells develop from radial glia to IPCs and then decreases as IPCs progress to neurons. Recent evidence suggests that EOMES and IPCs may also play a role neurogenesis in the adult hippocampal SGZ (5). EOMES is also a key transcription factor for memory T cells and for full effector differentiation of CD8+ T cells (6). Expression of EOMES is induced in CD8+ T cells following viral infection and bacterial infection where sufficient IL-12 has been produced to elicit acute host cell response (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Western Blotting

Background: The bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase or PFKFB) catalyzes the synthesis and degradation of fructose 2,6-bisphosphate and regulates its steady-state level (1,2). Fructose 2,6-bisphosphate activates phosphofructokinase, a rate-limiting enzyme in glycolysis, by allosteric regulation (1,2). Four different PFKFB isoforms (PFKFB1, PFKFB2, PFKFB3, and PFKFB4) have been identified (1,2). One of them, PFKFB3/iPFK-2, was shown to be inducible by hypoxia leading to increased glycolysis under hypoxic conditions (2). Research studies have shown that PFKFB3/iPFK-2 is also highly expressed in some types of human cancer (3).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunofluorescence (Frozen), Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: The NDRG (N-Myc downstream-regulated gene) family consisting of NDRG1, NDRG2, NDRG3, and NDRG4 are structurally related proteins with roles in cell proliferation, differentiation, apoptosis, stress responses, and cell migration/metastasis (1-3). NDRG1 was originally identified as a protein that was upregulated in N-Myc knockout mice (1). Proteins in the NDRG family, particularly NDRG1 and NDRG2, have been reported to be down-regulated in various cancer tissues and have been suggested to function as a tumor suppressors (4,5).

$108
250 PCR reactions
500 µl
SimpleChIP® Human ZNF335 Promoter Primers contain a mix of forward and reverse PCR primers that are specific to a region of the human zinc finger protein 335 (ZNF335) promoter. These primers can be used to amplify DNA that has been isolated using chromatin immunoprecipitation (ChIP). Primers have been optimized for use in SYBR® Green quantitative real-time PCR and have been tested in conjunction with SimpleChIP® Enzymatic Chromatin IP Kits #9004 and #9005 and ChIP-validated antibodies from Cell Signaling Technology®.
REACTIVITY
Human

Background: The chromatin immunoprecipitation (ChIP) assay is a powerful and versatile technique used for probing protein-DNA interactions within the natural chromatin context of the cell (1,2). This assay can be used to either identify multiple proteins associated with a specific region of the genome or to identify the many regions of the genome bound by a particular protein (3-6). ChIP can be used to determine the specific order of recruitment of various proteins to a gene promoter or to "measure" the relative amount of a particular histone modification across an entire gene locus (3,4). In addition to histone proteins, the ChIP assay can be used to analyze binding of transcription factors and co-factors, DNA replication factors, and DNA repair proteins. When performing the ChIP assay, cells are first fixed with formaldehyde, a reversible protein-DNA cross-linking agent that "preserves" the protein-DNA interactions occurring in the cell (1,2). Cells are lysed and chromatin is harvested and fragmented using either sonication or enzymatic digestion. Fragmented chromatin is then immunoprecipitated with antibodies specific to a particular protein or histone modification. Any DNA sequences that are associated with the protein or histone modification of interest will co-precipitate as part of the cross-linked chromatin complex and the relative amount of that DNA sequence will be enriched by the immunoselection process. After immunoprecipitation, the protein-DNA cross-links are reversed and the DNA is purified. Standard PCR or quantitative real-time PCR are often used to measure the amount of enrichment of a particular DNA sequence by a protein-specific immunoprecipitation (1,2). Alternatively, the ChIP assay can be combined with genomic tiling micro-array (ChIP on chip) techniques, high throughput sequencing (ChIP-Seq), or cloning strategies, all of which allow for genome-wide analysis of protein-DNA interactions and histone modifications (5-8). SimpleChIP® primers have been optimized for amplification of ChIP-isolated DNA using real-time quantitative PCR and provide important positive and negative controls that can be used to confirm a successful ChIP experiment.

$111
20 µl
$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunoprecipitation, Western Blotting

Background: Patched1 and 2 (PTCH1 and PTCH2) are twelve-pass transmembrane proteins that function as the receiving receptors for members of the Hedgehog family of proteins (1-4). In the absence of Hedgehog proteins, PTCH suppresses the otherwise constitutively active signaling receptor Smoothened (Smo) so that the Hedgehog signaling pathway is in the off state (5,6). Deactivating mutations that impair the ability of PTCH1 to suppress Smo are frequently found in patients with nevoid basal cell carcinoma syndrome (7,8). PTCH proteins have a sterol-sensing domain (SSD) also found in several proteins that function in cholesterol homeostasis, such as HMGCR (3-hydroxy-3-methylglutaryl coenzyme A-reductase) and SCAP (sterol regulatory element-binding protein-cleavage activating protein). However, the role of the SSD in Patched proteins is not clear (9,10).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunofluorescence (Frozen), Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: Cyclin-dependent kinases (CDKs) are serine/threonine kinases that are activated by cyclins and govern eukaryotic cell cycle progression. While CDK5 shares high sequence homology with its family members, it is thought mainly to function in postmitotic neurons, regulating the cytoarchitecture of these cells. Analogous to cyclins, p35 and p39 associate with and activate CDK5 despite the lack of sequence homology. CDK5 is ubiquitously expressed, but high levels of kinase activity are detected primarily in the nervous system due to the narrow expression pattern of p35 and p39 in post-mitotic neurons. A large number of CDK5 substrates have been identified although no discrete substrates have been attributed as a function of p35 vs. p39. Amongst many, substrates of CDK5 include p35 and p39. p35 is rapidly degraded (T1/2 <20 min) by the ubiquitin-proteasome pathway (1). However, p35 stability increases as CDK5 kinase activity decreases, and this is likely a result of decreased phosphorylation of p35 at Thr138 by CDK5 (2). NGF activates Erk and EGR1, and induces p35 expression in PC12 cells (3). Proteolytic cleavage of p35 by calpain produces p25 upon neurotoxic insult, resulting in prolonged activation of CDK5 by p25. Accumulation of p25 is found in neurodegenerative diseases such as Alzheimer's disease and Amyotrophic Lateral Sclerosis (ALS) (4-5).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Bim/Bod is a pro-apoptotic protein belonging to the BH3-only group of Bcl-2 family members including Bad, Bid, Bik, Hrk, and Noxa that contain a BH3 domain but lack other conserved BH1 or BH2 domains (1,2). Bim induces apoptosis by binding to and antagonizing anti-apoptotic members of the Bcl-2 family. Interactions have been observed with Bcl-2, Bcl-xL, Mcl-1, Bcl-w, Bfl-1, and BHRF-1 (1,2). Bim functions in regulating apoptosis associated with thymocyte negative selection and following growth factor withdrawal, during which Bim expression is elevated (3-6). Three major isoforms of Bim are generated by alternative splicing: BimEL, BimL, and BimS (1). The shortest form, BimS, is the most cytotoxic and is generally only transiently expressed during apoptosis. The BimEL and BimL isoforms may be sequestered to the dynein motor complex through an interaction with the dynein light chain and released from this complex during apoptosis (7). Apoptotic activity of these longer isoforms may be regulated by phosphorylation (8,9). Environmental stress triggers Bim phosphorylation by JNK and results in its dissociation from the dynein complex and increased apoptotic activity.

$111
20 µl
$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Flow Cytometry, IHC-Leica® Bond™, Immunofluorescence (Immunocytochemistry), Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: Bim/Bod is a pro-apoptotic protein belonging to the BH3-only group of Bcl-2 family members including Bad, Bid, Bik, Hrk, and Noxa that contain a BH3 domain but lack other conserved BH1 or BH2 domains (1,2). Bim induces apoptosis by binding to and antagonizing anti-apoptotic members of the Bcl-2 family. Interactions have been observed with Bcl-2, Bcl-xL, Mcl-1, Bcl-w, Bfl-1, and BHRF-1 (1,2). Bim functions in regulating apoptosis associated with thymocyte negative selection and following growth factor withdrawal, during which Bim expression is elevated (3-6). Three major isoforms of Bim are generated by alternative splicing: BimEL, BimL, and BimS (1). The shortest form, BimS, is the most cytotoxic and is generally only transiently expressed during apoptosis. The BimEL and BimL isoforms may be sequestered to the dynein motor complex through an interaction with the dynein light chain and released from this complex during apoptosis (7). Apoptotic activity of these longer isoforms may be regulated by phosphorylation (8,9). Environmental stress triggers Bim phosphorylation by JNK and results in its dissociation from the dynein complex and increased apoptotic activity.

$327
100 µl
This Cell Signaling Technology antibody is conjugated to biotin under optimal conditions. The biotinylated antibody is expected to exhibit the same species cross-reactivity as the unconjugated Phospho-IGF-I Receptor β (Tyr1135/1136)/Insulin Receptor β (Tyr1150/1151) (19H7) Rabbit mAb #3024.
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Western Blotting

Background: Type I insulin-like growth factor receptor (IGF-IR) is a transmembrane receptor tyrosine kinase that is widely expressed in many cell lines and cell types within fetal and postnatal tissues (1-3). Receptor autophosphorylation follows binding of the IGF-I and IGF-II ligands. Three tyrosine residues within the kinase domain (Tyr1131, Tyr1135, and Tyr1136) are the earliest major autophosphorylation sites (4). Phosphorylation of these three tyrosine residues is necessary for kinase activation (5,6). Insulin receptors (IRs) share significant structural and functional similarity with IGF-I receptors, including the presence of an equivalent tyrosine cluster (Tyr1146/1150/1151) within the kinase domain activation loop. Tyrosine autophosphorylation of IRs is one of the earliest cellular responses to insulin stimulation (7). Autophosphorylation begins with phosphorylation at Tyr1146 and either Tyr1150 or Tyr1151, while full kinase activation requires triple tyrosine phosphorylation (8).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Type I insulin-like growth factor receptor (IGF-IR) is a transmembrane receptor tyrosine kinase that is widely expressed in many cell lines and cell types within fetal and postnatal tissues (1-3). Receptor autophosphorylation follows binding of the IGF-I and IGF-II ligands. Three tyrosine residues within the kinase domain (Tyr1131, Tyr1135, and Tyr1136) are the earliest major autophosphorylation sites (4). Phosphorylation of these three tyrosine residues is necessary for kinase activation (5,6). Insulin receptors (IRs) share significant structural and functional similarity with IGF-I receptors, including the presence of an equivalent tyrosine cluster (Tyr1146/1150/1151) within the kinase domain activation loop. Tyrosine autophosphorylation of IRs is one of the earliest cellular responses to insulin stimulation (7). Autophosphorylation begins with phosphorylation at Tyr1146 and either Tyr1150 or Tyr1151, while full kinase activation requires triple tyrosine phosphorylation (8).

$122
20 µl
$307
100 µl
$719
300 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Western Blotting

Background: Type I insulin-like growth factor receptor (IGF-IR) is a transmembrane receptor tyrosine kinase that is widely expressed in many cell lines and cell types within fetal and postnatal tissues (1-3). Receptor autophosphorylation follows binding of the IGF-I and IGF-II ligands. Three tyrosine residues within the kinase domain (Tyr1131, Tyr1135, and Tyr1136) are the earliest major autophosphorylation sites (4). Phosphorylation of these three tyrosine residues is necessary for kinase activation (5,6). Insulin receptors (IRs) share significant structural and functional similarity with IGF-I receptors, including the presence of an equivalent tyrosine cluster (Tyr1146/1150/1151) within the kinase domain activation loop. Tyrosine autophosphorylation of IRs is one of the earliest cellular responses to insulin stimulation (7). Autophosphorylation begins with phosphorylation at Tyr1146 and either Tyr1150 or Tyr1151, while full kinase activation requires triple tyrosine phosphorylation (8).

$303
100 µl
APPLICATIONS
REACTIVITY
Hamster, Human, Monkey, Mouse, Rat

Application Methods: Western Blotting

Background: Stathmin is a ubiquitously expressed microtubule destabilizing phosphoprotein that is upregulated in a number of cancers. The amino terminus of the protein contains multiple phosphorylation sites and is involved in the promotion of tubulin filament depolymerization. Phosphorylation at these sites inactivates the protein and stabilizes microtubules. Ser16 phosphorylation by CaM kinases II and IV (1,2) increases during G2/M-phase and is involved in mitotic spindle regulation (3,4). Ser38 is a target for cdc2 kinase (5) and TNF-induced cell death gives rise to reactive oxygen intermediates leading to hyperphosphorylation of stathmin (6). EGF receptor activation of Rac and cdc42 also increases phosphorylation of stathmin on Ser16 and Ser38 (7). Other closely related family members are neuronally expressed and include SCG10, SCLIP, RB3 and its splice variants RB3' and RB3''. Stathmin and SCG10 have been shown to play roles in neuronal-like development in PC-12 cells (8).

$111
20 µl
$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: SHP-2 (PTPN11) is a ubiquitously expressed, nonreceptor protein tyrosine phosphatase (PTP). It participates in signaling events downstream of receptors for growth factors, cytokines, hormones, antigens, and extracellular matrices in the control of cell growth, differentiation, migration, and death (1). Activation of SHP-2 and its association with Gab1 is critical for sustained Erk activation downstream of several growth factor receptors and cytokines (2). In addition to its role in Gab1-mediated Erk activation, SHP-2 attenuates EGF-dependent PI3 kinase activation by dephosphorylating Gab1 at p85 binding sites (3). SHP-2 becomes phosphorylated at Tyr542 and Tyr580 in its carboxy-terminus in response to growth factor receptor activation (4). These phosphorylation events are thought to relieve basal inhibition and stimulate SHP-2 tyrosine phosphatase activity (5). Mutations in the corresponding gene result in a pair of clinically similar disorders (Noonan syndrome and LEOPARD syndrome) that may result from abnormal MAPK regulation (6).

$303
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunofluorescence (Frozen), Immunoprecipitation, Western Blotting

Background: Mutations in Doublecortin cause Lissencephaly (smooth brain), a neuronal migration disorder characterized by epilepsy and mental retardation (1). Doublecortin is a microtubule associated protein that stabilizes and bundles microtubules. A conserved doublecortin domain mediates the interaction with microtubules, and interestingly most missense mutations cluster in this domain (2). Kinases JNK, CDK5 and PKA phosphorylate doublecortin. JNK phosphorylates Thr321, Thr331 and Ser334 while PKA phosphorylates Ser47 and CDK5 phosphorylates Ser297 (3-5). Phosphorylation of Ser297 lowers the affinity of doublecortin to microtubules. Furthermore, mutations of Ser297 result in migration defects (5).

$303
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: SHP-2 (PTPN11) is a ubiquitously expressed, nonreceptor protein tyrosine phosphatase (PTP). It participates in signaling events downstream of receptors for growth factors, cytokines, hormones, antigens, and extracellular matrices in the control of cell growth, differentiation, migration, and death (1). Activation of SHP-2 and its association with Gab1 is critical for sustained Erk activation downstream of several growth factor receptors and cytokines (2). In addition to its role in Gab1-mediated Erk activation, SHP-2 attenuates EGF-dependent PI3 kinase activation by dephosphorylating Gab1 at p85 binding sites (3). SHP-2 becomes phosphorylated at Tyr542 and Tyr580 in its carboxy-terminus in response to growth factor receptor activation (4). These phosphorylation events are thought to relieve basal inhibition and stimulate SHP-2 tyrosine phosphatase activity (5). Mutations in the corresponding gene result in a pair of clinically similar disorders (Noonan syndrome and LEOPARD syndrome) that may result from abnormal MAPK regulation (6).