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EMBO J. 1997 Sep 15;16(18):5592-9.

Growth factor activation of MAP kinase requires cell adhesion.

Author information

1
Department of Vascular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA.

Abstract

The MAP kinase pathway is a major regulator of both normal and oncogenic growth. We report that activation of the MAP kinase ERK2 by serum or purified growth factors is strongly dependent on cell adhesion to extracellular matrix proteins. This effect is specific to soluble growth factors, since suspended cells still activate ERK2 in response to plating on fibronectin, and is reversible. Analysis of endogenous Ras and Raf show that these proteins are still activated by serum in suspended cells, whereas MEK activity is inhibited. Conversely, activation of ERK2 by activated mutants of Ras and Raf is still adhesion-dependent but activation by MEK is not. Consistent with these results, activated MEK enhances growth of ras-transformed cells in suspension but not when adherent. These results identify a novel synergism between cell adhesion- and growth factor-regulated pathways, and explain how oncogenic activation of MAP kinases induces both serum- and anchorage-independent growth.

PMID:
9312018
PMCID:
PMC1170191
DOI:
10.1093/emboj/16.18.5592
[Indexed for MEDLINE]
Free PMC Article

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