Microsize antibodies for $99 | Learn More >>

Hamster Nuclear Membrane

$260
100 µl
APPLICATIONS
REACTIVITY
Bovine, Dog, Hamster, Human, Monkey, Mouse, Pig, Rat

Application Methods: Western Blotting

Background: The 90 kDa ribosomal S6 kinases (RSK1-4) are a family of widely expressed Ser/Thr kinases characterized by two nonidentical, functional kinase domains (1) and a carboxy-terminal docking site for extracellular signal-regulated kinases (ERKs) (2). Several sites both within and outside of the RSK kinase domain, including Ser380, Thr359, Ser363, and Thr573, are important for kinase activation (3). RSK1-3 are activated via coordinated phosphorylation by MAPKs, autophosphorylation, and phosphoinositide-3-OH kinase (PI3K) in response to many growth factors, polypeptide hormones, and neurotransmitters (3).

$489
96 assays
1 Kit
The PathScan® Total YB1 Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of YB1 protein. A YB1 rabbit antibody has been coated onto the microwells. After incubation with cell lysates, YB1 protein is captured by the coated antibody. Following extensive washing, a YB1 mouse detection antibody is added to detect the captured YB1 protein. Anti-mouse IgG, HRP-linked antibody is then used to recognize the bound detection antibody. HRP substrate, TMB, is added to develop color. The magnitude of the absorbance for the developed color is proportional to the quantity of YB1 protein.Antibodies in kit are custom formulations specific to kit.
REACTIVITY
Hamster, Human, Monkey, Mouse, Rat

Background: The Y-box binding protein 1 (YB1) belongs to a family of evolutionarily conserved, multifunctional Y-box proteins that bind single-stranded DNA and RNA and function as regulators of transcription, RNA metabolism, and protein synthesis (1). YB1 binds to Y-box sequences (TAACC) found in multiple gene promoters and can positively or negatively regulate transcription. YB1 activates genes associated with proliferation and cancer, such as cyclin A, cyclin B1, matrix metalloproteinase-2 (MMP-2), and the multi-drug resistance 1 (MDR1) gene (2-4). YB1 represses genes associated with cell death, including the Fas cell death-associated receptor and the p53 tumor suppressor gene (5-7). It also interacts with the RNA-splicing factor SRp30c and stabilizes interleukin-2 (IL-2) mRNA upon induction of T lymphocytes by IL-2 (8,9). The majority of YB1 protein localizes to the cytoplasm, with a minor pool found in the nucleus; however, nuclear localization appears to be critical for its role in promoting proliferation. Nuclear translocation is cell cycle regulated, with YB1 protein accumulating in the nucleus during G1/S phase (2). In addition, nuclear translocation is induced in response to extracellular stimuli such as hyperthermia and UV irradiation, or treatment of cells with thrombin, interferons, or insulin-like growth factor (IGF-I) (2,10). Treatment of the MCF7 breast cancer cell line with IGF-I results in Akt-mediated phosphorylation of YB1 at Ser102, which is required for nuclear translocation of YB1 and its ability to promote anchorage-independent growth (10). Research studies have shown that YB1 is overexpressed in many malignant tissues, including breast cancer, non-small cell lung carcinoma, ovarian adenocarcinomas, human osteosarcomas, colorectal carcinomas, and malignant melanomas. Investigators have shown that nuclear YB1 expression correlates with high levels of proliferation, drug resistance, and poor tumor prognosis (2,7,10).

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

Application Methods: Western Blotting

Background: Ran is a small GTPase of the Ras family that plays a central role in the spacial and temperal organization of eukaryotic cells. During interphase, Ran-GDP localizes to the cytoplasm and Ran-GTP to the nucleus. This polarized localization of Ran ensures its role in nuclear transport (1). During mitosis, Ran-GTP is chromatin associated, where it promotes spindle assembly and nuclear envolope formation (1,2). In S phase, Ran-GTP associates with and inhibits MCM helicase, ensuring precise chromosomal DNA duplication during the cell cycle (3).

$303
100 µl
APPLICATIONS
REACTIVITY
Hamster, Human, Monkey

Application Methods: Western Blotting

Background: The entry of eukaryotic cells into mitosis is regulated by cdc2 kinase activation, a process controlled at several steps including cyclin binding and phosphorylation of cdc2 at Thr161 (1). However, the critical regulatory step in activating cdc2 during progression into mitosis appears to be dephosphorylation of cdc2 at Thr14 and Tyr15 (2). Phosphorylation at Thr14 and Tyr15, resulting in inhibition of cdc2, can be carried out by Wee1 and Myt1 protein kinases (3,4). The cdc25 phosphatase may be responsible for removal of phosphates at Thr14 and Tyr15 and subsequent activation of cdc2 (1,5).

$305
100 µl
This Cell Signaling Technology (CST) antibody is conjugated to the carbohydrate groups of horseradish peroxidase (HRP) via its amine groups. The HRP conjugated antibody is expected to exhibit the same species cross-reactivity as the unconjugated antibody (Histone H3 (3H1) Rabbit mAb #9717).
APPLICATIONS
REACTIVITY
Bovine, D. melanogaster, Dog, Hamster, Human, Monkey, Mouse, Pig, Rat, Zebrafish

Application Methods: Western Blotting

Background: Modulation of chromatin structure plays an important role in the regulation of transcription in eukaryotes. The nucleosome, made up of DNA wound around eight core histone proteins (two each of H2A, H2B, H3, and H4), is the primary building block of chromatin (1). The amino-terminal tails of core histones undergo various post-translational modifications, including acetylation, phosphorylation, methylation, and ubiquitination (2-5). These modifications occur in response to various stimuli and have a direct effect on the accessibility of chromatin to transcription factors and, therefore, gene expression (6). In most species, histone H2B is primarily acetylated at Lys5, 12, 15, and 20 (4,7). Histone H3 is primarily acetylated at Lys9, 14, 18, 23, 27, and 56. Acetylation of H3 at Lys9 appears to have a dominant role in histone deposition and chromatin assembly in some organisms (2,3). Phosphorylation at Ser10, Ser28, and Thr11 of histone H3 is tightly correlated with chromosome condensation during both mitosis and meiosis (8-10). Phosphorylation at Thr3 of histone H3 is highly conserved among many species and is catalyzed by the kinase haspin. Immunostaining with phospho-specific antibodies in mammalian cells reveals mitotic phosphorylation at Thr3 of H3 in prophase and its dephosphorylation during anaphase (11).

$122
20 µl
$303
100 µl
APPLICATIONS
REACTIVITY
D. melanogaster, Hamster, Human, Mouse

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

Background: Modulation of chromatin structure plays an important role in the regulation of transcription in eukaryotes. The nucleosome, made up of DNA wound around eight core histone proteins (two each of H2A, H2B, H3, and H4), is the primary building block of chromatin (1). The amino-terminal tails of core histones undergo various post-translational modifications, including acetylation, phosphorylation, methylation, and ubiquitination (2-5). These modifications occur in response to various stimuli and have a direct effect on the accessibility of chromatin to transcription factors and, therefore, gene expression (6). In most species, histone H2B is primarily acetylated at Lys5, 12, 15, and 20 (4,7). Histone H3 is primarily acetylated at Lys9, 14, 18, 23, 27, and 56. Acetylation of H3 at Lys9 appears to have a dominant role in histone deposition and chromatin assembly in some organisms (2,3). Phosphorylation at Ser10, Ser28, and Thr11 of histone H3 is tightly correlated with chromosome condensation during both mitosis and meiosis (8-10). Phosphorylation at Thr3 of histone H3 is highly conserved among many species and is catalyzed by the kinase haspin. Immunostaining with phospho-specific antibodies in mammalian cells reveals mitotic phosphorylation at Thr3 of H3 in prophase and its dephosphorylation during anaphase (11).

$260
100 µl
APPLICATIONS
REACTIVITY
Bovine, D. melanogaster, Dog, Hamster, Human, Monkey, Mouse, Pig, Rat, Zebrafish

Application Methods: Western Blotting

Background: Modulation of chromatin structure plays an important role in the regulation of transcription in eukaryotes. The nucleosome, made up of DNA wound around eight core histone proteins (two each of H2A, H2B, H3, and H4), is the primary building block of chromatin (1). The amino-terminal tails of core histones undergo various post-translational modifications, including acetylation, phosphorylation, methylation, and ubiquitination (2-5). These modifications occur in response to various stimuli and have a direct effect on the accessibility of chromatin to transcription factors and, therefore, gene expression (6). In most species, histone H2B is primarily acetylated at Lys5, 12, 15, and 20 (4,7). Histone H3 is primarily acetylated at Lys9, 14, 18, 23, 27, and 56. Acetylation of H3 at Lys9 appears to have a dominant role in histone deposition and chromatin assembly in some organisms (2,3). Phosphorylation at Ser10, Ser28, and Thr11 of histone H3 is tightly correlated with chromosome condensation during both mitosis and meiosis (8-10). Phosphorylation at Thr3 of histone H3 is highly conserved among many species and is catalyzed by the kinase haspin. Immunostaining with phospho-specific antibodies in mammalian cells reveals mitotic phosphorylation at Thr3 of H3 in prophase and its dephosphorylation during anaphase (11).

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

Application Methods: Immunoprecipitation, Western Blotting

Background: The entry of eukaryotic cells into mitosis is regulated by cdc2 kinase activation, a process controlled at several steps including cyclin binding and phosphorylation of cdc2 at Thr161 (1). However, the critical regulatory step in activating cdc2 during progression into mitosis appears to be dephosphorylation of cdc2 at Thr14 and Tyr15 (2). Phosphorylation at Thr14 and Tyr15, resulting in inhibition of cdc2, can be carried out by Wee1 and Myt1 protein kinases (3,4). The cdc25 phosphatase may be responsible for removal of phosphates at Thr14 and Tyr15 and subsequent activation of cdc2 (1,5).

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

Application Methods: Western Blotting

Background: Reptin/RuvBL2 and Pontin/RuvBL1 are closely related members of the AAA+ (ATPase associated with diverse cellular activities) superfamily of proteins, and are putatively homologous to bacterial RuvB proteins that drive branch migration of Holliday junctions (1). Reptin and Pontin function together as essential components of chromatin remodeling and modification complexes, such as INO80, TIP60, SRCAP, and Uri1, which play key roles in regulating gene transcription (1,2). In their capacity as essential transcriptional co-regulators, Reptin and Pontin have both been implicated in oncogenic transformations, including those driven by c-Myc, β-catenin, and E1A (2-7).

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

Application Methods: Western Blotting

Background: The DEAD box family of RNA helicases is characterized in part by a common D-E-A-D amino acid motif. The family is composed of a growing number of proteins found in a wide range of organisms from bacteria to mammals. DEAD helicases have distinct biological functions in RNA metabolism and ribonucleoprotein (RNP) processing (reviewed in 1,2).DDX3 is a DEAD box family RNA helicase with diverse cellular functions. DDX3 is required for nuclear export of HIV-1 viral transcripts, possibly in a complex with the viral Rev protein and host cofactor CRM1 (3). DDX3 is required for hepatitis C virus (HCV) RNA replication (4) and its expression is downregulated in hepatitis B virus (HBV) associated hepatocellular carcinoma (HCC) (5).Recent evidence suggests that DDX3 functions as a tumor suppressor protein. Its expression inhibits tumor cell colony formation and increases expression of the cdk inhibitor p21 Waf1/Cip1. Low DDX3 expression has been shown in HCC (5,6), and aberrant subcellular localization occurs in many squamous cell carcinomas (6). Reduced DDX3 expression in cultured cells causes a diminished dependence on serum for cell proliferation and changes in cyclin D1 and p21 Waf1/Cip1 expression (5).DDX3 is phosphorylated at Thr204 and Thr323 by the mitotic cyclin dependent kinase, cyclin B/cdc2. This phosphorylation is thought to cause a loss of DDX3 function and a concomitant repression of ribosome biogenesis and translation in mitosis (7).

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

Application Methods: Western Blotting

Background: Cofilin and actin-depolymerization factor (ADF) are members of a family of essential conserved small actin-binding proteins that play pivotal roles in cytokinesis, endocytosis, embryonic development, stress response, and tissue regeneration (1). In response to stimuli, cofilin promotes the regeneration of actin filaments by severing preexisting filaments (2). The severing activity of cofilin is inhibited by LIMK or TESK phosphorylation at Ser3 of cofilin (3-5). Phosphorylation at Ser3 also regulates cofilin translocation from the nucleus to the cytoplasm (6).

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

Application Methods: Western Blotting

Background: The minichromosome maintenance (MCM) 2-7 proteins are a family of six related proteins required for initiation and elongation of DNA replication. MCM2-7 bind together to form the heterohexameric MCM complex that is thought to act as a replicative helicase at the DNA replication fork (1-5). This complex is a key component of the pre-replication complex (pre-RC) (reviewed in 1). Cdc6 and CDT1 recruit the MCM complex to the origin recognition complex (ORC) during late mitosis/early G1 phase forming the pre-RC and licensing the DNA for replication (reviewed in 2). Licensing of the chromatin permits the DNA to replicate only once per cell cycle, thereby helping to ensure that genetic alterations and malignant cell growth do not occur (reviewed in 3). Phosphorylation of the MCM2, MCM3, MCM4, and MCM6 subunits appears to regulate MCM complex activity and the initiation of DNA synthesis (6-8). CDK1 phosphorylation of MCM3 at Ser112 during late mitosis/early G1 phase has been shown to initiate complex formation and chromatin loading in vitro (8). Phosphorylation of MCM2 at serine 139 by cdc7/dbf4 coincides with the initiation of DNA replication (9). MCM proteins are removed during DNA replication, causing chromatin to become unlicensed through inhibition of pre-RC reformation. Studies have shown that the MCM complex is involved in checkpoint control by protecting the structure of the replication fork and assisting in restarting replication by recruiting checkpoint proteins after arrest (reviewed in 3,10).

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

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

Background: The Stat3 transcription factor is an important signaling molecule for many cytokines and growth factor receptors (1) and is required for murine fetal development (2). Research studies have shown that Stat3 is constitutively activated in a number of human tumors (3,4) and possesses oncogenic potential (5) and anti-apoptotic activities (3). Stat3 is activated by phosphorylation at Tyr705, which induces dimerization, nuclear translocation, and DNA binding (6,7). Transcriptional activation seems to be regulated by phosphorylation at Ser727 through the MAPK or mTOR pathways (8,9). Stat3 isoform expression appears to reflect biological function as the relative expression levels of Stat3α (86 kDa) and Stat3β (79 kDa) depend on cell type, ligand exposure, or cell maturation stage (10). It is notable that Stat3β lacks the serine phosphorylation site within the carboxy-terminal transcriptional activation domain (8).

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

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

Background: The minichromosome maintenance (MCM) 2-7 proteins are a family of six related proteins required for initiation and elongation of DNA replication. MCM2-7 bind together to form the heterohexameric MCM complex that is thought to act as a replicative helicase at the DNA replication fork (1-5). This complex is a key component of the pre-replication complex (pre-RC) (reviewed in 1). Cdc6 and CDT1 recruit the MCM complex to the origin recognition complex (ORC) during late mitosis/early G1 phase forming the pre-RC and licensing the DNA for replication (reviewed in 2). Licensing of the chromatin permits the DNA to replicate only once per cell cycle, thereby helping to ensure that genetic alterations and malignant cell growth do not occur (reviewed in 3). Phosphorylation of the MCM2, MCM3, MCM4, and MCM6 subunits appears to regulate MCM complex activity and the initiation of DNA synthesis (6-8). CDK1 phosphorylation of MCM3 at Ser112 during late mitosis/early G1 phase has been shown to initiate complex formation and chromatin loading in vitro (8). Phosphorylation of MCM2 at serine 139 by cdc7/dbf4 coincides with the initiation of DNA replication (9). MCM proteins are removed during DNA replication, causing chromatin to become unlicensed through inhibition of pre-RC reformation. Studies have shown that the MCM complex is involved in checkpoint control by protecting the structure of the replication fork and assisting in restarting replication by recruiting checkpoint proteins after arrest (reviewed in 3,10).

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

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

Background: The minichromosome maintenance (MCM) 2-7 proteins are a family of six related proteins required for initiation and elongation of DNA replication. MCM2-7 bind together to form the heterohexameric MCM complex that is thought to act as a replicative helicase at the DNA replication fork (1-5). This complex is a key component of the pre-replication complex (pre-RC) (reviewed in 1). Cdc6 and CDT1 recruit the MCM complex to the origin recognition complex (ORC) during late mitosis/early G1 phase forming the pre-RC and licensing the DNA for replication (reviewed in 2). Licensing of the chromatin permits the DNA to replicate only once per cell cycle, thereby helping to ensure that genetic alterations and malignant cell growth do not occur (reviewed in 3). Phosphorylation of the MCM2, MCM3, MCM4, and MCM6 subunits appears to regulate MCM complex activity and the initiation of DNA synthesis (6-8). CDK1 phosphorylation of MCM3 at Ser112 during late mitosis/early G1 phase has been shown to initiate complex formation and chromatin loading in vitro (8). Phosphorylation of MCM2 at serine 139 by cdc7/dbf4 coincides with the initiation of DNA replication (9). MCM proteins are removed during DNA replication, causing chromatin to become unlicensed through inhibition of pre-RC reformation. Studies have shown that the MCM complex is involved in checkpoint control by protecting the structure of the replication fork and assisting in restarting replication by recruiting checkpoint proteins after arrest (reviewed in 3,10).

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

Application Methods: Western Blotting

Background: The origin recognition complex (ORC) is a highly conserved heterohexameric protein complex that associates with DNA at or near initiation of DNA replication sites. All six ORC subunits are essential for initiation of DNA replication (1-3), and ORC may be involved in regulation of gene expression in response to stress (4). ORC binding to DNA permits the ordered binding of other proteins such as cdc6 and MCMs to form pre-replication complexes (Pre-RCs). Pre-RCs form between telophase and early G1 phase of the cell cycle and are inactivated at the onset of DNA synthesis, allowing coordinated regulation of DNA replication and cell division (5). Modification of one or more of the six ORC subunits may be responsible for its inactivation during S phase, but the chromatin binding behavior of the ORC subunits during the cell division cycle is still under investigation (6-7).

$489
96 assays
1 Kit
The PathScan® Total β-Actin Sandwich ELISA Kit is a solid phase sandwich enzyme-linked immunosorbent assay (ELISA) that detects endogenous levels of β-actin. A β-actin rabbit antibody has been coated onto the microwells. After incubation with cell lysates, β-actin is captured by the coated antibody. Following extensive washing, a pan-actin mouse detection antibody is added to detect the captured β-actin. An anti-mouse IgG, HRP-linked antibody is then used to recognize the bound detection antibody. HRP substrate (TMB) is added to develop color. The magnitude of the absorbance for this developed color is proportional to the quantity of β-actin.Antibodies in kit are custom formulations specific to kit.
REACTIVITY
Hamster, Human, Monkey, Mouse, Rat

Background: Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are predominantly expressed in nonmuscle cells, controlling cell structure and motility (1). α-cardiac and α-skeletal actin are expressed in striated cardiac and skeletal muscles, respectively; two smooth muscle actins, α- and γ-actin, are found primarily in vascular smooth muscle and enteric smooth muscle, respectively. These actin isoforms regulate the contractile potential of muscle cells (1). Actin exists mainly as a fibrous polymer, F-actin. In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (2). The ARP2/3 complex stabilizes F-actin fragments and promotes formation of new actin filaments (2). Research studies have shown that actin is hyperphosphorylated in primary breast tumors (3). Cleavage of actin under apoptotic conditions has been observed in vitro and in cardiac and skeletal muscle, as shown in research studies (4-6). Actin cleavage by caspase-3 may accelerate ubiquitin/proteasome-dependent muscle proteolysis (6).

$106
20 µl
$260
100 µl
APPLICATIONS
REACTIVITY
Dog, Hamster, Human, Monkey, Mouse, Rat

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

Background: Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are predominantly expressed in nonmuscle cells, controlling cell structure and motility (1). α-cardiac and α-skeletal actin are expressed in striated cardiac and skeletal muscles, respectively; two smooth muscle actins, α- and γ-actin, are found primarily in vascular smooth muscle and enteric smooth muscle, respectively. These actin isoforms regulate the contractile potential of muscle cells (1). Actin exists mainly as a fibrous polymer, F-actin. In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (2). The ARP2/3 complex stabilizes F-actin fragments and promotes formation of new actin filaments (2). Research studies have shown that actin is hyperphosphorylated in primary breast tumors (3). Cleavage of actin under apoptotic conditions has been observed in vitro and in cardiac and skeletal muscle, as shown in research studies (4-6). Actin cleavage by caspase-3 may accelerate ubiquitin/proteasome-dependent muscle proteolysis (6).

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

Application Methods: Immunoprecipitation, Western Blotting

Background: The origin recognition complex (ORC) is a highly conserved heterohexameric protein complex that associates with DNA at or near initiation of DNA replication sites. All six ORC subunits are essential for initiation of DNA replication (1-3), and ORC may be involved in regulation of gene expression in response to stress (4). ORC binding to DNA permits the ordered binding of other proteins such as cdc6 and MCMs to form pre-replication complexes (Pre-RCs). Pre-RCs form between telophase and early G1 phase of the cell cycle and are inactivated at the onset of DNA synthesis, allowing coordinated regulation of DNA replication and cell division (5). Modification of one or more of the six ORC subunits may be responsible for its inactivation during S phase, but the chromatin binding behavior of the ORC subunits during the cell division cycle is still under investigation (6-7).

$260
100 µl
$630
300 µl
APPLICATIONS
REACTIVITY
Bovine, D. melanogaster, Hamster, Human, Mink, Monkey, Mouse, Rat, Zebrafish

Application Methods: Western Blotting

Background: Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are predominantly expressed in nonmuscle cells, controlling cell structure and motility (1). α-cardiac and α-skeletal actin are expressed in striated cardiac and skeletal muscles, respectively; two smooth muscle actins, α- and γ-actin, are found primarily in vascular smooth muscle and enteric smooth muscle, respectively. These actin isoforms regulate the contractile potential of muscle cells (1). Actin exists mainly as a fibrous polymer, F-actin. In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (2). The ARP2/3 complex stabilizes F-actin fragments and promotes formation of new actin filaments (2). Research studies have shown that actin is hyperphosphorylated in primary breast tumors (3). Cleavage of actin under apoptotic conditions has been observed in vitro and in cardiac and skeletal muscle, as shown in research studies (4-6). Actin cleavage by caspase-3 may accelerate ubiquitin/proteasome-dependent muscle proteolysis (6).