title: Infrequent activation of mitogen-activated protein kinase in human colon cancers.
abstract: OBJECTIVE
  Mitogen-activated protein kinase (MAPK) is a downstream factor of the Ras-Raf-MAPK cascade and it is now considered to be a key molecule in signaling processes stimulated by growth factors and differentiation inducers.
  
  
  METHODS
  We examined MAPK activity in 21 advanced colon cancers to investigate whether the MAPK cascade might play a role in the progression of colon cancers.
  
  
  RESULTS
  MAPK activation (3.9-10.1-fold) was observed in 4 of 21 cases (18%), but 3 cases (75%, 3 of 4 cases) showed MAPK activation without ras mutation, thus suggesting that MAPK activation did not correlate with the presence of Ki-ras mutations in these cases. Other kinds of oncogene activation would be involved to MAPK activation in human colon cancers. In other cases MAPK activation was not detected or partly down-regulated.
  
  
  CONCLUSIONS
  These findings suggest that positive and negative regulation of MAPK activity are associated with loss of normal growth control and may be involved in carcinogenesis of colon cancers.
authors.affiliation: First Department of Surgery, Kyoto Prefectural University of Medicine, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Sakakura
authors.forename: A
authors.initials: A
authors.lastname: Hagiwara
authors.forename: T
authors.initials: T
authors.lastname: Shirahama
authors.forename: M
authors.initials: M
authors.lastname: Nakanishi
authors.forename: R
authors.initials: R
authors.lastname: Yasuoka
authors.forename: Y
authors.initials: Y
authors.lastname: Fujita
authors.forename: J
authors.initials: J
authors.lastname: Inazawa
authors.forename: T
authors.initials: T
authors.lastname: Abe
authors.forename: M
authors.initials: M
authors.lastname: Kohno
authors.forename: H
authors.initials: H
authors.lastname: Yamagishi
mesh_terms: D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D003106:Colon / Q000473:pathology; D003110:Colonic Neoplasms / Q000235:genetics* / Q000473:pathology; D004252:DNA Mutational Analysis; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009367:Neoplasm Staging; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology
chemical_list: D020928:Mitogen-Activated Protein Kinases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)