MST4, a new Ste20-related kinase that mediates cell growth and transformation via modulating ERK pathway

Oncogene. 2001 Oct 4;20(45):6559-69. doi: 10.1038/sj.onc.1204818.


In this study, we report the cloning and characterization of a novel human Ste20-related kinase that we designated MST4. The 416 amino acid full-length MST4 contains an amino-terminal kinase domain, which is highly homologous to MST3 and SOK, and a unique carboxy-terminal domain. Northern blot analysis indicated that MST4 is highly expressed in placenta, thymus, and peripheral blood leukocytes. Wild-type but not kinase-dead MST4 can phosphorylate myelin basic protein in an in vitro kinase assay. MST4 specifically activates ERK but not JNK or p38 MAPK in transient transfected cells or in stable cell lines. Overexpression of dominant negative MEK1 or treatment with PD98059 abolishes MST4-induced ERK activity, whereas dominant-negative Ras or c-Raf-1 mutants failed to do so, indicating MST4 activates MEK1/ERK via a Ras/Raf-1 independent pathway. HeLa and Phoenix cell lines overexpressing wild-type, but not kinase-dead, MST4 exhibit increased growth rate and form aggressive soft-agar colonies. These phenotypes can be inhibited by PD98059. These results provide the first evidence that MST4 is biologically active in the activation of MEK/ERK pathway and in mediating cell growth and transformation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Division
  • Cell Transformation, Neoplastic*
  • Cloning, Molecular
  • Humans
  • MAP Kinase Kinase 1
  • MAP Kinase Signaling System*
  • Mitogen-Activated Protein Kinase Kinases / physiology
  • Mitogen-Activated Protein Kinases / metabolism*
  • Models, Biological
  • Molecular Sequence Data
  • Neoplasms / etiology*
  • Neoplasms / pathology
  • Phylogeny
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / physiology*
  • RNA, Messenger / biosynthesis
  • Sequence Homology, Amino Acid
  • Tissue Distribution
  • Tumor Cells, Cultured


  • RNA, Messenger
  • STK26 protein, human
  • Protein-Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1
  • MAP2K1 protein, human
  • Mitogen-Activated Protein Kinase Kinases

Associated data

  • GENBANK/AF231012