Phospho-FoxO3a (Ser318/321) An

9465:

Immunoprecipitation , Western Blotting

Phospho-Fox03a (Ser318/321) Antibody detects endogenous levels of Fox03a only when phosphorylated at serine 318/321. The antibody is expected to cross-react with Fox01 when phosphorylated at serine 322/325 based on the peptide sequence.

Polyclonal antibodies are produced by immunizing animals with a synthetic peptide corresponding to the sequence of human Fox03a. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western blot analysis of extracts from serum starved and serum-treated NIH/3T3 cells as well as untreated and LY294002/Wortmannin-treated MDA-MB-468 cells, using Phospho-Fox03a (Ser318/321) Antibody (upper) or Akt Antibody #9272 (lower).

The Forkhead family of transcription factors is involved in tumorigenesis of rhabdomyosarcoma and acute leukemias (1-3). Within the family, three members (FoxO1, FoxO4, and FoxO3a) have sequence similarity to the nematode orthologue DAF-16, which mediates signaling via a pathway involving IGFR1, PI3K, and Akt (4-6). Active forkhead members act as tumor suppressors by promoting cell cycle arrest and apoptosis. Increased expression of any FoxO member results in the activation of the cell cycle inhibitor p27 Kip1. Forkhead transcription factors also play a part in TGF-β-mediated upregulation of p21 Cip1, a process negatively regulated through PI3K (7). Increased proliferation results when forkhead transcription factors are inactivated through phosphorylation by Akt at Thr24, Ser256, and Ser319, which results in nuclear export and inhibition of transcription factor activity (8). Forkhead transcription factors can also be inhibited by the deacetylase sirtuin (SirT1) (9).

Phosphorylation sites Ser322 and Ser325 of Fox01 are important for nuclear export and are homologous to Ser318 and Ser321 of Fox03a (9).

1. Anderson, M.J. et al. (1998) Genomics 47, 187-199.
2. Galili, N. et al. (1993) Nat. Genet. 5, 230-235.
3. Borkhardt, A. et al. (1997) Oncogene 14, 195-202.
4. Nakae, J. et al. (1999) J. Biol. Chem. 274, 15982-15985.
5. Rena, G. et al. (1999) J. Biol. Chem. 274, 17179-17183.
6. Guo, S. et al. (1999) J. Biol. Chem. 274, 17184-17192.
7. Seoane, J. et al. (2004) Cell 117, 211-223.
8. Arden, K.C. (2004) Mol. Cell 14, 416-418.
9. Yang, Y. et al. (2005) EMBO J. 24, 1021-1032.
10. Rena, G. et al. (2002) EMBO J. 21, 2263-2271.

• Jag, U.R. et al. (2009) Mol Endocrinol 23, 1587-602. Applications: Western Blotting

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• 9271 Phospho-Akt (Ser473) Antibody
• 9272 Akt Antibody
• 9275 Phospho-Akt (Thr308) Antibody
• 9461 Phospho-FoxO1 (Ser256) Antibody
• 9464 Phospho-FoxO1 (Thr24)/FoxO3a (Thr32) Antibody
• 9471 Phospho-FoxO4 (Ser193) Antibody
• 9472 FoxO4 Antibody
• 9901 LY294002 (PI3 Kinase Inhibitor)
• 9951 Wortmannin
• 7071 Phototope^® -HRP Western Blot Detection System, Anti-rabbit IgG, HRP-linked Antibody
• 7074 Anti-rabbit IgG, HRP-linked Antibody
• 7720 Prestained Protein Marker, Broad Range (Premixed Format)
• 7727 Biotinylated Protein Ladder Detection Pack
• 7003 20X LumiGLO^® Reagent and 20X Peroxide

For Research Use Only. Not For Use In Diagnostic Procedures.