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Updated: Jul 7, 2026

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods
07:49

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods

Published on: July 17, 2019

Site-specific phosphorylation of raf in cells containing oncogenic ras-p21 is likely mediated by jun-N-terminal

Victor Adler1, Wilbur Bowne, Josef Michl

  • 1Department of Pathology, SUNY Downstate Medical Center, Brooklyn, New York, USA.

Annals of Clinical and Laboratory Science
|March 5, 2008
PubMed

Insights

This study reveals that oncogenic ras-p21 triggers phosphorylation of both raf-Ser259 and raf-Ser338. JNK signaling appears to mediate raf-Ser259 phosphorylation, impacting raf

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • Cancer research

Background:

  • The raf-MEK-MAPK (ERK) and JNK-jun pathways are crucial in cellular processes.
  • Previous work indicated JNK can phosphorylate raf, but not vice versa.

Purpose of the Study:

  • To elucidate the mechanism of JNK-induced raf phosphorylation.
  • To investigate the differential phosphorylation of raf-Ser259 and raf-Ser338 in response to various stimuli.

Main Methods:

  • In vitro kinase assays using immunobead-bound raf and activated JNK.
  • Oocyte maturation experiments induced by oncogenic or wild-type ras-p21 and insulin.
  • Analysis of human pancreatic cancer cells (MIA-PaCa-2) treated with a ras peptide.

Main Results:

  • Activated JNK strongly phosphorylates raf at Ser259 and Ser338 in vitro.
  • Oncogenic ras-p21 induces phosphorylation at both sites in oocytes, while insulin primarily affects Ser338.
  • In MIA-PaCa-2 cells, oncogenic ras-p21 leads to phosphorylation of both serines, with a peptide inhibitor reducing Ser259 phosphorylation.

Conclusions:

  • Oncogenic ras-p21 signaling promotes phosphorylation of both raf-Ser259 and raf-Ser338.
  • JNK activation is implicated in the phosphorylation of raf-Ser259.
  • These findings offer insights into raf pathway regulation in cancer.

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