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Erk1/2 MAP kinases are required for epidermal G2/M progression
Correspondence to Paul A. Khavari: khavari{at}stanford.edu
Erk1/2 mitogen-activated protein kinases (MAPKs) are often hyperactivated in human cancers, where they affect multiple processes, including proliferation. However, the effects of Erk1/2 loss in normal epithelial tissue, the setting of most extracellular signal-regulated kinase (Erk)–associated neoplasms, are unknown. In epidermis, loss of Erk1 or Erk2 individually has no effect, whereas simultaneous Erk1/2 depletion inhibits cell division, demonstrating that these MAPKs are necessary for normal tissue self-renewal. Growth inhibition caused by Erk1/2 loss is rescued by reintroducing Erk2, but not by activating Erk effectors that promote G1 cell cycle progression. Unlike fibroblasts, in which Erk1/2 loss decreases cyclin D1 expression and induces G1/S arrest, Erk1/2 loss in epithelial cells reduces cyclin B1 and c-Fos expression and induces G2/M arrest while disrupting a gene regulatory network centered on cyclin B1–Cdc2. Thus, the cell cycle stages at which Erk1/2 activity is required vary by cell type, with Erk1/2 functioning in epithelial cells to enable progression through G2/M.
© 2009 Dumesic et al.
This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
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