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Monoclonal Antibody Western Blotting Tissue Development

$303
100 µl
APPLICATIONS
REACTIVITY
Human

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

Background: Wilms' Tumor 1 (WT1) is a transcription factor named from Wilms' Tumor 1, an embryonal malignancy of the kidneys that is caused by mutations in the WT1 gene (1). It is highly important in development, particularly of the genitourinary system, and mutations and dysregulation of expression of WT1 result in a variety of syndromes affecting the genitourinal system and other tissues (2-5).WT1 has a myriad of biological functions and a host of interacting partners and target genes (6). It can behave as a transcriptional activator, or a repressor, and can act as an oncogene or a tumor suppressor (7). It exerts influence over the epigenetic landscape, and also has post translational influence of gene expression through RNA interactions (8). The diverse biological roles of WT1 have been attributed to the existence of multiple isoforms and post translation modifications of the protein (9).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse

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

Background: DHCR24/Seladin-1 was identified as a molecular basis for desmosterolosis (1). It encodes for 24-dehydrocholesterol reductase (3β-hydroxysterol Δ-24-reductase). This enzyme reduces desmosterol in cholesterol biosynthesis (1). Recessive mutations in this gene in desmosterolosis patients lead to a defective enzyme resulting in increased levels of desmosterol (1). DHCR24/Seladin-1 is induced upon oxidative stress and was found to mediate Ras-induced senescence resulting from increased reactive oxygen species (2). Studies further indicate that the level of DHCR24/Seladin-1 is induced in the acute response and reduced in the chronic response to oxidative stress in a cholesterol dependent manner (3). Moreover, overexpression of DHCR24/Seladin-1 bearing two mutations that abolish its reductase acitivity causes the cells to lose protection from oxidative stress (3). These findings thus link the reductase activity of DHCR24/Seladin-1 to its protective role in oxidative stress. This enzyme has also been demonstrated to be a hydrogen peroxide scavenger (4).

$122
20 µl
$293
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

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

Background: GATA proteins comprise a group of transcription factors that are related by the presence of conserved zinc finger DNA binding domains, which bind directly to the nucleotide sequence core element GATA (1-3). There are six vertebrate GATA proteins, designated GATA-1 to GATA-6 (3).

$293
100 µl
APPLICATIONS
REACTIVITY
Human

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

Background: GATA proteins comprise a group of transcription factors that are related by the presence of conserved zinc finger DNA binding domains, which bind directly to the nucleotide sequence core element GATA (1-3). There are six vertebrate GATA proteins, designated GATA-1 to GATA-6 (3).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Western Blotting

Background: Wilms' Tumor 1 (WT1) is a transcription factor named from Wilms' Tumor 1, an embryonal malignancy of the kidneys that is caused by mutations in the WT1 gene (1). It is highly important in development, particularly of the genitourinary system, and mutations and dysregulation of expression of WT1 result in a variety of syndromes affecting the genitourinal system and other tissues (2-5).WT1 has a myriad of biological functions and a host of interacting partners and target genes (6). It can behave as a transcriptional activator, or a repressor, and can act as an oncogene or a tumor suppressor (7). It exerts influence over the epigenetic landscape, and also has post translational influence of gene expression through RNA interactions (8). The diverse biological roles of WT1 have been attributed to the existence of multiple isoforms and post translation modifications of the protein (9).

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

Application Methods: Chromatin IP, Western Blotting

Background: Methyl-CpG-binding protein 2 (MeCP2) is the founding member of a family of methyl-CpG-binding domain (MBD) proteins that also includes MBD1, MBD2, MBD3, MBD4, MBD5 and MBD6 (1-3). Apart from MBD3, these proteins bind methylated cytosine residues in the context of the di-nucleotide 5´-CG-3´ to establish and maintain regions of transcriptionally inactive chromatin by recruiting a variety of co-repressor proteins (2). MeCP2 recruits histone deacetylases HDAC1 and HDAC2, and the DNA methyltransferase DNMT1 (4-6). MBD1 couples transcriptional silencing to DNA replication and interacts with the histone methyltransferases ESET and SUV39H1 (7,8). MBD2 and MBD3 co-purify as part of the NuRD (nucleosome remodeling and histone de-acetylation) co-repressor complex, which contains the chromatin remodeling ATPase Mi-2, HDAC1 and HDAC2 (9,10). MBD5 and MBD6 have recently been identified and little is known regarding their protein interactions. MBD proteins are associated with cancer and other diseases; MBD4 is best characterized for its role in DNA repair and MBD2 has been linked to intestinal cancer (11,12). Mutations in the MeCP2 gene cause the neurologic developmental disorder Rett Syndrome (13). MeCP2 protein levels are high in neurons, where it plays a critical role in multiple synaptic processes (14). In response to various physiological stimuli, MeCP2 is phosphorylated on Ser421 and regulates the expression of genes controlling dendritic patterning and spine morphogenesis (14). Disruption of this process in individuals with altered MeCP2 may cause the pathological changes seen in Rett Syndrome.

$293
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Chromatin IP, Chromatin IP-seq, Immunofluorescence (Immunocytochemistry), Immunoprecipitation, Western Blotting

Background: The orphan nuclear receptor, steroidogenic factor 1 (STF-1, also called Ad4BP), is encoded by the NR5A1 gene and plays an instrumental role in directing the transcriptional control of steroidogenesis (1). Initially identified as a tissue-specific transcriptional regulator of cytochrome P450 steroid hydroxylases, research studies of both global (2) and tissue-specific knockout mice (3-6) have demonstrated that STF-1 is required for the development of adrenal glands, gonads, ventromedial hypothalamus, and for the proper functioning of pituitary gonadotropes. Indeed, humans with mutations that render STF-1 transcriptionally inactive can present with testicular failure, ovarian failure, and adrenal insufficiency (7,8). Furthermore, dysregulation of STF-1 has been linked to diseases such as endometriosis (9) and adrenocortical carcinoma (10).Like other nuclear hormone receptors, STF-1 has a modular domain structure composed of an amino-terminal zinc finger DNA-binding domain, a ligand-binding domain, a carboxy-terminal AF-2 activation domain, and a hinge region with AF-1-like activation activity. STF-1 also contains a fushi tarazu factor 1 box, which functions as an accessory DNA binding domain (11). STF-1 is primarily phosphorylated at Ser203, which is thought to enhance its transcriptional activity by promoting complex formation with transcriptional cofactors (12). In addition to phosphorylation at Ser203, STF-1 is subject to SUMO conjugation and acetylation at ε-amino groups of target lysine residues. Whereas SUMOylation represses STF-1 function (13,14), acetylation enhances its transcriptional activity (15).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunofluorescence (Immunocytochemistry), Western Blotting

Background: Connective tissue growth factor (CTGF, CCN2) belongs to the CCN (CYR61, CTGF, NOV) family of secreted extracellular matrix (ECM) proteins (1). Members of this family contain four conserved cysteine-rich domains, and interact in the ECM with a diverse array of cell surface receptors, including integrins and heparin-sulfate proteoglycans (2). These interactions regulate a multitude of cellular and tissue functions, including adhesion, proliferation, migration, differentiation, senescence, angiogenesis, inflammation, and wound repair (1, 3-5). The CTGF gene is a transcriptional target of both YAP/TAZ and TGFβ-SMAD signaling pathways (6,7), and aberrant regulation of CTGF expression is strongly associated with pathological conditions, notably cancer and fibrosis (8, 9).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Western Blotting

Background: Connective tissue growth factor (CTGF, CCN2) belongs to the CCN (CYR61, CTGF, NOV) family of secreted extracellular matrix (ECM) proteins (1). Members of this family contain four conserved cysteine-rich domains, and interact in the ECM with a diverse array of cell surface receptors, including integrins and heparin-sulfate proteoglycans (2). These interactions regulate a multitude of cellular and tissue functions, including adhesion, proliferation, migration, differentiation, senescence, angiogenesis, inflammation, and wound repair (1, 3-5). The CTGF gene is a transcriptional target of both YAP/TAZ and TGFβ-SMAD signaling pathways (6,7), and aberrant regulation of CTGF expression is strongly associated with pathological conditions, notably cancer and fibrosis (8, 9).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Western Blotting

Background: TIMPs are members of the family of tissue inhibitor of matrix metalloproteinases (MMPs) that includes TIMP1, TIMP2, TIMP3, and TIMP4. The main function of TIMPs is their inhibitory effect on MMPs. TIMPs irreversibly inactivate MMPs by direct binding to their catalytic zinc cofactor and resultant inhibition of proteinase function (1,2). In addition to MMP inhibition, TIMPs have also been shown to interact with various membrane receptors on the cell surface. Some of these interactions include: TIMP1 with CD63, TIMP2 with α3β1 integrin, and TIMP3 with VEGFR2, all of which result in distinct cellular effects (3). TIMPs are involved in a wide variety of biological functions, such as tumor angiogenesis and progression (4,5), wound healing, and vascular remodeling (6,7). Mutations in TIMP3 are associated with Sorsby's fundus dystrophy (8,9).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey

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

Background: RPA70 (HSSB, REPA1, RF-A, RP-A, p70) is a component of a heterotrimeric complex, composed of 70, 32/30 and 14 kDa subunits, collectively known as RPA. RPA is a single stranded DNA binding protein, whose DNA binding activity is believed to reside entirely in the 70 kDa subunit. The complex is required for almost all aspects of cellular DNA metabolism such as DNA replication (1-3), recombination, cell cycle and DNA damage checkpoints, and all major types of DNA repair including nucleotide excision, base excision, mismatch and double-strand break repairs (4-7). In response to genotoxic stress in eukaryotic cells, RPA has been shown to associate with the Rad9/Rad1/Hus1 (9-1-1) checkpoint complex (8). RPA is hyperphosphorylated upon DNA damage or replication stress by checkpoint kinases including ataxia telangiectasia mutated (ATM), ATM and Rad3-related (ATR), and DNA-dependent protein kinase (DNA-PK) (9-11). Phosphorylation of RPA32 occurs at serines 4, 8 and 33 (11). Hyperphosphorylation may alter RPA-DNA and RPA-protein interactions. In addition to the checkpoint partners, RPA interacts with a wide variety of protein partners, including proteins required for normal replication such as RCF, PCNA and Pol α, and also proteins involved in SV40 replication, such as DNA polymerase I and SV40 large T antigen (10,12).

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

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

Background: The p53 tumor suppressor protein plays a major role in cellular response to DNA damage and other genomic aberrations. Activation of p53 can lead to either cell cycle arrest and DNA repair or apoptosis (1). p53 is phosphorylated at multiple sites in vivo and by several different protein kinases in vitro (2,3). DNA damage induces phosphorylation of p53 at Ser15 and Ser20 and leads to a reduced interaction between p53 and its negative regulator, the oncoprotein MDM2 (4). MDM2 inhibits p53 accumulation by targeting it for ubiquitination and proteasomal degradation (5,6). p53 can be phosphorylated by ATM, ATR, and DNA-PK at Ser15 and Ser37. Phosphorylation impairs the ability of MDM2 to bind p53, promoting both the accumulation and activation of p53 in response to DNA damage (4,7). Chk2 and Chk1 can phosphorylate p53 at Ser20, enhancing its tetramerization, stability, and activity (8,9). p53 is phosphorylated at Ser392 in vivo (10,11) and by CAK in vitro (11). Phosphorylation of p53 at Ser392 is increased in human tumors (12) and has been reported to influence the growth suppressor function, DNA binding, and transcriptional activation of p53 (10,13,14). p53 is phosphorylated at Ser6 and Ser9 by CK1δ and CK1ε both in vitro and in vivo (13,15). Phosphorylation of p53 at Ser46 regulates the ability of p53 to induce apoptosis (16). Acetylation of p53 is mediated by p300 and CBP acetyltransferases. Inhibition of deacetylation suppressing MDM2 from recruiting HDAC1 complex by p19 (ARF) stabilizes p53. Acetylation appears to play a positive role in the accumulation of p53 protein in stress response (17). Following DNA damage, human p53 becomes acetylated at Lys382 (Lys379 in mouse) in vivo to enhance p53-DNA binding (18). Deacetylation of p53 occurs through interaction with the SIRT1 protein, a deacetylase that may be involved in cellular aging and the DNA damage response (19).

$327
100 µl
This Cell Signaling Technology (CST) antibody is conjugated to biotin under optimal conditions.
APPLICATIONS
REACTIVITY
Human

Application Methods: Western Blotting

Background: The p53 tumor suppressor protein plays a major role in cellular response to DNA damage and other genomic aberrations. Activation of p53 can lead to either cell cycle arrest and DNA repair or apoptosis (1). p53 is phosphorylated at multiple sites in vivo and by several different protein kinases in vitro (2,3). DNA damage induces phosphorylation of p53 at Ser15 and Ser20 and leads to a reduced interaction between p53 and its negative regulator, the oncoprotein MDM2 (4). MDM2 inhibits p53 accumulation by targeting it for ubiquitination and proteasomal degradation (5,6). p53 can be phosphorylated by ATM, ATR, and DNA-PK at Ser15 and Ser37. Phosphorylation impairs the ability of MDM2 to bind p53, promoting both the accumulation and activation of p53 in response to DNA damage (4,7). Chk2 and Chk1 can phosphorylate p53 at Ser20, enhancing its tetramerization, stability, and activity (8,9). p53 is phosphorylated at Ser392 in vivo (10,11) and by CAK in vitro (11). Phosphorylation of p53 at Ser392 is increased in human tumors (12) and has been reported to influence the growth suppressor function, DNA binding, and transcriptional activation of p53 (10,13,14). p53 is phosphorylated at Ser6 and Ser9 by CK1δ and CK1ε both in vitro and in vivo (13,15). Phosphorylation of p53 at Ser46 regulates the ability of p53 to induce apoptosis (16). Acetylation of p53 is mediated by p300 and CBP acetyltransferases. Inhibition of deacetylation suppressing MDM2 from recruiting HDAC1 complex by p19 (ARF) stabilizes p53. Acetylation appears to play a positive role in the accumulation of p53 protein in stress response (17). Following DNA damage, human p53 becomes acetylated at Lys382 (Lys379 in mouse) in vivo to enhance p53-DNA binding (18). Deacetylation of p53 occurs through interaction with the SIRT1 protein, a deacetylase that may be involved in cellular aging and the DNA damage response (19).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse

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

Background: Embryonic stem cells (ESC) derived from the inner cell mass of the blastocyst are unique in their pluripotent capacity and potential for self-renewal (1). Research studies demonstrate that a set of transcription factors that includes Oct-4, Sox2, and Nanog forms a transcriptional network that maintains cells in a pluripotent state (2,3). Chromatin immunoprecipitation experiments show that Sox2 and Oct-4 bind to thousands of gene regulatory sites, many of which regulate cell pluripotency and early embryonic development (4,5). siRNA knockdown of either Sox2 or Oct-4 results in loss of pluripotency (6). Induced overexpression of Oct-4 and Sox2, along with additional transcription factors Klf4 and c-Myc, can reprogram both mouse and human somatic cells to a pluripotent state (7,8). Additional evidence demonstrates that Sox2 is also present in adult multipotent progenitors that give rise to some adult epithelial tissues, including several glands, the glandular stomach, testes, and cervix. Sox2 is thought to regulate target gene expression important for survival and regeneration of these tissues (9).

$122
20 µl
$303
100 µl
$717
300 µl
APPLICATIONS
REACTIVITY
Human

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

Background: The p53 tumor suppressor protein plays a major role in cellular response to DNA damage and other genomic aberrations. Activation of p53 can lead to either cell cycle arrest and DNA repair or apoptosis (1). p53 is phosphorylated at multiple sites in vivo and by several different protein kinases in vitro (2,3). DNA damage induces phosphorylation of p53 at Ser15 and Ser20 and leads to a reduced interaction between p53 and its negative regulator, the oncoprotein MDM2 (4). MDM2 inhibits p53 accumulation by targeting it for ubiquitination and proteasomal degradation (5,6). p53 can be phosphorylated by ATM, ATR, and DNA-PK at Ser15 and Ser37. Phosphorylation impairs the ability of MDM2 to bind p53, promoting both the accumulation and activation of p53 in response to DNA damage (4,7). Chk2 and Chk1 can phosphorylate p53 at Ser20, enhancing its tetramerization, stability, and activity (8,9). p53 is phosphorylated at Ser392 in vivo (10,11) and by CAK in vitro (11). Phosphorylation of p53 at Ser392 is increased in human tumors (12) and has been reported to influence the growth suppressor function, DNA binding, and transcriptional activation of p53 (10,13,14). p53 is phosphorylated at Ser6 and Ser9 by CK1δ and CK1ε both in vitro and in vivo (13,15). Phosphorylation of p53 at Ser46 regulates the ability of p53 to induce apoptosis (16). Acetylation of p53 is mediated by p300 and CBP acetyltransferases. Inhibition of deacetylation suppressing MDM2 from recruiting HDAC1 complex by p19 (ARF) stabilizes p53. Acetylation appears to play a positive role in the accumulation of p53 protein in stress response (17). Following DNA damage, human p53 becomes acetylated at Lys382 (Lys379 in mouse) in vivo to enhance p53-DNA binding (18). Deacetylation of p53 occurs through interaction with the SIRT1 protein, a deacetylase that may be involved in cellular aging and the DNA damage response (19).

$122
20 µl
$293
100 µl
APPLICATIONS
REACTIVITY
Human, Rat

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

Background: Cyclins are a family of proteins that activate specific cyclin-dependent kinases required for progression through the cell cycle. The entry of all eukaryotic cells into mitosis is regulated by activation of cdc2/cdk1 at the G2/M transition. This activation is a multi-step process that begins with the binding of the regulatory subunit, cyclin B1, to cdc2/cdk1 to form the mitosis-promoting factor (MPF). MPF remains in the inactive state until phosphorylation of cdc2/cdk1 at Thr161 by cdk activating kinase (CAK) (1,2) and dephosphorylation of cdc2/cdk1 at Thr14/Tyr15 by cdc25C (3-5). Five cyclin B1 phosphorylation sites (Ser116, 126, 128, 133, and 147) are located in the cytoplasmic retention signal (CRS) domain and are thought to regulate the translocation of cyclin B1 to the nucleus at the G2/M checkpoint, promoting nuclear accumulation and initiation of mitosis (6-9). While MPF itself can phosphorylate Ser126 and Ser128, polo-like kinase 1 (PLK1) phosphorylates cyclin B1 preferentially at Ser133 and possibly at Ser147 (6,10). At the end of mitosis, cyclin B1 is targeted for degradation by the anaphase-promoting complex (APC), allowing for cell cycle progression (11). Research studies have shown that cyclin B1 is overexpressed in breast, prostate, and non-small cell lung cancers (12-14).

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

Application Methods: Immunohistochemistry (Paraffin), Western Blotting

Background: Gelsolin (actin-depolymerizing factor, ADF, AGEL, Brevin) is an 83 kDa protein that shares structural and functional homology to villin and adseverin/scinderin (1,2). Gelsolin plays an important role in actin filament assembly by capping and severing actin proteins in a Ca2+-dependent manner (3,4). Gelsolin is important for cellular events (e.g., membrane ruffling, chemotaxis, ciliogenesis) that require cytoskeletal remodeling (3). Accordingly, cells from gelsolin knockout mice exhibit motility defects, including a failure to ruffle in response to growth factor stimulation (5,6). In humans, defects in gelsolin have been linked to amyloidosis type 5 (AMYL5), a hereditary disease characterized by cranial neuropathy, which appears to result from gelsolin amyloid deposition (7).

$115
20 µl
$269
100 µl
APPLICATIONS
REACTIVITY
Human

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

Background: Bcl-2 exerts a survival function in response to a wide range of apoptotic stimuli through inhibition of mitochondrial cytochrome c release (1). It has been implicated in modulating mitochondrial calcium homeostasis and proton flux (2). Several phosphorylation sites have been identified within Bcl-2 including Thr56, Ser70, Thr74, and Ser87 (3). It has been suggested that these phosphorylation sites may be targets of the ASK1/MKK7/JNK1 pathway and that phosphorylation of Bcl-2 may be a marker for mitotic events (4,5). Mutation of Bcl-2 at Thr56 or Ser87 inhibits its anti-apoptotic activity during glucocorticoid-induced apoptosis of T lymphocytes (6). Interleukin-3 and JNK-induced Bcl-2 phosphorylation at Ser70 may be required for its enhanced anti-apoptotic functions (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse

Application Methods: Chromatin IP, Chromatin IP-seq, Flow Cytometry, Immunofluorescence (Frozen), Immunofluorescence (Immunocytochemistry), Immunoprecipitation, Western Blotting

Background: Embryonic stem cells (ESC) derived from the inner cell mass of the blastocyst are unique in their pluripotent capacity and potential for self-renewal (1). Research studies demonstrate that a set of transcription factors that includes Oct-4, Sox2, and Nanog forms a transcriptional network that maintains cells in a pluripotent state (2,3). Chromatin immunoprecipitation experiments show that Sox2 and Oct-4 bind to thousands of gene regulatory sites, many of which regulate cell pluripotency and early embryonic development (4,5). siRNA knockdown of either Sox2 or Oct-4 results in loss of pluripotency (6). Induced overexpression of Oct-4 and Sox2, along with additional transcription factors Klf4 and c-Myc, can reprogram both mouse and human somatic cells to a pluripotent state (7,8). Additional evidence demonstrates that Sox2 is also present in adult multipotent progenitors that give rise to some adult epithelial tissues, including several glands, the glandular stomach, testes, and cervix. Sox2 is thought to regulate target gene expression important for survival and regeneration of these tissues (9).

$269
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Chromatin IP, Flow Cytometry, Immunofluorescence (Immunocytochemistry), Immunohistochemistry (Paraffin), Western Blotting

Background: The p53 tumor suppressor protein plays a major role in cellular response to DNA damage and other genomic aberrations. Activation of p53 can lead to either cell cycle arrest and DNA repair or apoptosis (1). p53 is phosphorylated at multiple sites in vivo and by several different protein kinases in vitro (2,3). DNA damage induces phosphorylation of p53 at Ser15 and Ser20 and leads to a reduced interaction between p53 and its negative regulator, the oncoprotein MDM2 (4). MDM2 inhibits p53 accumulation by targeting it for ubiquitination and proteasomal degradation (5,6). p53 can be phosphorylated by ATM, ATR, and DNA-PK at Ser15 and Ser37. Phosphorylation impairs the ability of MDM2 to bind p53, promoting both the accumulation and activation of p53 in response to DNA damage (4,7). Chk2 and Chk1 can phosphorylate p53 at Ser20, enhancing its tetramerization, stability, and activity (8,9). p53 is phosphorylated at Ser392 in vivo (10,11) and by CAK in vitro (11). Phosphorylation of p53 at Ser392 is increased in human tumors (12) and has been reported to influence the growth suppressor function, DNA binding, and transcriptional activation of p53 (10,13,14). p53 is phosphorylated at Ser6 and Ser9 by CK1δ and CK1ε both in vitro and in vivo (13,15). Phosphorylation of p53 at Ser46 regulates the ability of p53 to induce apoptosis (16). Acetylation of p53 is mediated by p300 and CBP acetyltransferases. Inhibition of deacetylation suppressing MDM2 from recruiting HDAC1 complex by p19 (ARF) stabilizes p53. Acetylation appears to play a positive role in the accumulation of p53 protein in stress response (17). Following DNA damage, human p53 becomes acetylated at Lys382 (Lys379 in mouse) in vivo to enhance p53-DNA binding (18). Deacetylation of p53 occurs through interaction with the SIRT1 protein, a deacetylase that may be involved in cellular aging and the DNA damage response (19).