Evidence for cell-specific differences in transformation by N-, H- and K-ras

Oncogene. 1995 Oct 19;11(8):1639-47.


Although Ras plays a fundamental role in cellular proliferation, differentiation and transformation, clear functional differences between the three major Ras proteins (N-, H- and K-Ras) have not as yet been demonstrated. In this study, chimeric constructs were used to compare directly transformation by N-, H- and K-ras oncogenes. In Rat-2 and NIH3T3 fibroblasts, transformation assays (anchorage independence, focus-formation and growth in 1% FCS) showed that H12-Ras was more transforming than N12-Ras or K12-Ras. By contrast, in the human multipotent haemopoietic cell line, TF-1, N12-Ras exhibited greater biological activity. Northern blotting and protein analyses indicated that these findings were not the result of differences in expression or stability of p21Ras. Using further H-ras/N-ras chimeric constructs, we found that the greater transforming activity of H12-Ras in fibroblasts was not due to the hypervariable-CAAX region, but rather to unique sequences between amino acids 84 and 143. These data demonstrate cell specific differences in the intrinsic transforming potential of N-ras, H-ras and K-ras oncogenes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Cell Adhesion
  • Cell Division
  • Cell Transformation, Neoplastic / genetics*
  • Cells, Cultured
  • DNA Primers / chemistry
  • Fibroblasts / cytology
  • Gene Expression
  • Genes, ras
  • Hematopoietic Stem Cells / cytology
  • Humans
  • Molecular Sequence Data
  • Oncogenes
  • Point Mutation
  • RNA, Messenger / genetics
  • Rats


  • DNA Primers
  • RNA, Messenger