Ras- and mitogen-activated protein kinase kinase-dependent and - independent pathways in p21(Cip2/Waf1) induction by fibroblast growth factor- 2, platelet-derived growth factor, and transforming growth factor-β1

Laura Kivinen, Marikki Laiho

Research output: Contribution to journalArticlepeer-review

Abstract

p21(Waf1/Cip1) (hereafter referred to as p21) is upregulated in differentiating and DNA-damaged cells, but it is also up-regulated by serum and growth factors. We show here that fibroblast growth factor-2 (FGF-2), platelet-derived growth factor (PDGF), and transforming growth factor-β1 (TGF-β1) all induce p21 expression in mouse fibroblasts, but with markedly different kinetics. We link their effect on p21 to Ras and mitogen-activated protein kinase kinase-1(/2) [MEK1(/2)]-regulated pathways using either a specific MEK1(/2) inhibitor (PD 098059) or cells expressing conditionally activated Ras or dominant negative Ras. We demonstrate that p21 induction by PDGF and TGF-β1 requires MEK1(/2) and, additionally, that the TGF-β1 effect on p21 depends on Ras, whereas the PDGF effect does not. In contrast, FGF-2 regulation of p21 is largely independent of MEK and Ras. However, PD 098059 efficiently inhibited S-phase entry of quiescent cells induced by either FGF- 2 or PDGF, suggesting separate signaling pathways for FGF-2 in induction of p21 and in S-phase entry. The results suggest different but partly overlapping signaling pathways in growth factor regulation of p21.

Original languageEnglish (US)
Pages (from-to)621-628
Number of pages8
JournalCell Growth and Differentiation
Volume10
Issue number9
StatePublished - Sep 1 1999
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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