Inactivation of the Wip1 phosphatase inhibits mammary tumorigenesis through p38 MAPK-mediated activation of the p16(Ink4a)-p19(Arf) pathway

Nat Genet. 2004 Apr;36(4):343-50. doi: 10.1038/ng1317. Epub 2004 Feb 29.


Modulation of tumor suppressor activities may provide new opportunities for cancer therapy. Here we show that disruption of the gene Ppm1d encoding Wip1 phosphatase activated the p53 and p16 (also called Ink4a)-p19 (also called ARF) pathways through p38 MAPK signaling and suppressed in vitro transformation of mouse embryo fibroblasts (MEFs) by oncogenes. Disruption of the gene Cdkn2a (encoding p16 and p19), but not of Trp53 (encoding p53), reconstituted cell transformation in Ppm1d-null MEFs. In vivo, deletion of Ppm1d in mice bearing mouse mammary tumor virus (MMTV) promoter-driven oncogenes Erbb2 (also called c-neu) or Hras1 impaired mammary carcinogenesis, whereas reduced expression of p16 and p19 by methylation-induced silencing or inactivation of p38 MAPK correlated with tumor appearance. We conclude that inactivation or depletion of the Wip1 phosphatase with resultant p38 MAPK activation suppresses tumor appearance by modulating the Cdkn2a tumor-suppressor locus.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cyclin-Dependent Kinase Inhibitor p16 / metabolism*
  • Mammary Neoplasms, Experimental / enzymology
  • Mammary Neoplasms, Experimental / metabolism
  • Mammary Neoplasms, Experimental / pathology*
  • Mice
  • Mice, Transgenic
  • Mitogen-Activated Protein Kinases / metabolism*
  • Neoplasm Proteins / antagonists & inhibitors*
  • Neoplasm Proteins / metabolism
  • Phosphoprotein Phosphatases / antagonists & inhibitors*
  • Phosphoprotein Phosphatases / metabolism
  • Protein Phosphatase 2C
  • Tumor Suppressor Protein p14ARF / metabolism*
  • Tumor Suppressor Protein p53 / metabolism
  • p38 Mitogen-Activated Protein Kinases


  • Cdkn2a protein, mouse
  • Cyclin-Dependent Kinase Inhibitor p16
  • Neoplasm Proteins
  • Tumor Suppressor Protein p14ARF
  • Tumor Suppressor Protein p53
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Phosphoprotein Phosphatases
  • Ppm1d protein, mouse
  • Protein Phosphatase 2C