Rac GTPase activity is essential for lipopolysaccharide signaling to extracellular signal-regulated kinase and p38 MAP kinase activation in Rat-2 fibroblasts

Chang Hoon Woo, Jae-Hong Kim

Research output: Contribution to journalArticle

30 Citations (Scopus)


Lipopolysaccharide (LPS) has potent proinflammatory properties by acting on many cell types. Recently, mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinasc (ERK), p38 kinase, and c-jun N-terminal kinase (JNK) were shown to be involved in signal transduction in response to LPS. However, the detailed mechanism of LPS-induced signaling in the cell, especially the role of the Rho family GTPases remains largely unknown. In the present study, we investigated the role of Rac1, a member of the Rho family GTPases, in the LPS-induced MAPKs activation in Rat-2 fibroblasts. Our results showed that LPS induced the activation of ERK and p38 MAP kinase in a Rac-dependent manner, suggesting a mediatory role of Racl in LPS signaling to MAPKs stimulation. We also observed that LPS caused a time-dependent activation of Rac1. In addition, our results have shown that pretreatment with herbimycin or wortmannin dramatically inhibited Rac1 activation induced by LPS. These suggest that tyrosine kinase(s) and phosphatidylinositol 3-kinase (PI 3-kinase) are possibly acting upstream of Rac1 in the LPS signaling to MAPKs.

Original languageEnglish
Pages (from-to)470-475
Number of pages6
JournalMolecules and Cells
Issue number3
Publication statusPublished - 2002 Jun 1



  • ERK
  • Lipopolysaccharide
  • p38 Kinase
  • Rac

ASJC Scopus subject areas

  • Cell Biology
  • Genetics
  • Molecular Biology

Cite this