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Product Description

Nonphosphorylated Stat1 Control Cell Extracts: Total cell extracts from HeLa cells prepared without treatment serve as a negative control. Supplied in SDS Sample Buffer.

Phosphorylated Stat1 Control Cell Extracts: Total cell extracts from HeLa cells prepared with 100 ng/ml interferon-alpha 5 minute treatment serve as a positive control. Supplied in SDS Sample Buffer.


The Stat1 transcription factor is activated in response to a large number of ligands (1) and is essential for responsiveness to IFN-α and IFN-γ (2,3). Phosphorylation of Stat1 at Tyr701 induces Stat1 dimerization, nuclear translocation, and DNA binding (4). Stat1 protein exists as a pair of isoforms, Stat1α (91 kDa) and the splice variant Stat1β (84 kDa). In most cells, both isoforms are activated by IFN-α, but only Stat1α is activated by IFN-γ. The inappropriate activation of Stat1 occurs in many tumors (5). In addition to tyrosine phosphorylation, Stat1 is also phosphorylated at Ser727 through a p38 mitogen-activated protein kinase (MAPK)-dependent pathway in response to IFN-α and other cellular stresses (6). Serine phosphorylation may be required for the maximal induction of Stat1-mediated gene activation.


1.  Heim, M.H. (2001) J Recept Signal Transduct Res 19, 75-120.

2.  Ihle, J.N. et al. (1994) Trends Biochem. Sci. 19, 222-227.

3.  Durbin, J.E. et al. (1996) Cell 84, 443-50.

4.  Meraz, M.A. et al. (1996) Cell 84, 431-42.

5.  Wen, Z. et al. (1995) Cell 82, 241-50.

6.  Frank, D.A. (1999) Mol. Med. 5, 432-456.



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