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Updated: Mar 22, 2026

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods
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ERK1/2-induced phosphorylation of R-Ras GTPases stimulates their oncogenic potential

C Frémin1, J-P Guégan1, C Plutoni1

  • 1Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec, Canada.

Oncogene
|April 19, 2016
PubMed

Insights

Phosphorylation of R-Ras proteins TC21 and R-Ras by ERK1/2 MAP kinases stimulates their activity and oncogenic potential. This discovery reveals a new regulatory mechanism controlling cancer cell behavior.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Signaling

Background:

  • R-Ras family proteins (TC21, R-Ras, M-Ras) are small GTPases implicated in cancer.
  • Overexpression and activated mutants of R-Ras proteins can induce cell transformation.
  • Regulation of R-Ras protein activity is poorly understood, with few activating mutations reported in human cancers.

Purpose of the Study:

  • To investigate the post-translational modification and regulation of R-Ras family proteins.
  • To identify novel mechanisms controlling the oncogenic potential of TC21 and R-Ras.
  • To elucidate the role of phosphorylation in R-Ras protein function.

Main Methods:

  • In vitro and in vivo phosphorylation assays using MAP kinases ERK1/2.
  • Analysis of phosphorylation-defective mutants in cell adhesion, migration, and invasion assays.
  • Tumorigenicity studies in immunodeficient mice.

Main Results:

  • TC21 and R-Ras are phosphorylated on a conserved C-terminal serine residue (Ser186 and Ser201, respectively) by ERK1/2.
  • Phosphorylation stimulates R-Ras protein activation without affecting localization or stability.
  • Phosphorylation-defective mutants show impaired cancer cell adhesion and migration/invasion.
  • Phosphorylation of TC21 and R-Ras enhances their tumorigenic activity in vivo.

Conclusions:

  • A novel regulatory mechanism for TC21 and R-Ras involves phosphorylation by ERK1/2.
  • This phosphorylation event is crucial for potentiating the oncogenic activity of these GTPases.
  • Targeting this phosphorylation could offer new therapeutic strategies for cancers overexpressing R-Ras proteins.

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