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MEK is a negative regulator of Stat5b in PDGF‐stimulated cells
Author(s) -
Valgeirsdóttir Sigrı́dur,
Ruusala Aino,
Heldin Carl-Henrik
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00459-7
Subject(s) - phosphorylation , platelet derived growth factor receptor , microbiology and biotechnology , mitogen activated protein kinase , tyrosine phosphorylation , phosphorylation cascade , chemistry , kinase , protein phosphorylation , growth factor , cancer research , biology , protein kinase a , biochemistry , receptor
In this study we show that platelet‐derived growth factor (PDGF)‐induced DNA binding as well as transcriptional activation of Stat5b are markedly increased by inhibition of the MAP (mitogen‐activated protein) kinase kinase MEK. In addition to the previously demonstrated tyrosine phosphorylation, we show that serine and threonine phosphorylation of Stat5b is increased in response to PDGF stimulation. However, inhibition of MEK had no effect on the phosphorylation level of Stat5b or on the nuclear translocation of Stat5b. These observations indicate that MEK is a negative modulator of PDGF‐induced Stat5b activation through a mechanism not involving direct phosphorylation of Stat5b.