title: Activated N-ras gene was found in human hepatoma tissue but only in a small fraction of the tumor cells.
abstract: Activated N-ras gene was isolated from human hepatoma tissue by DNA transfection assay coupled with the neomycin selection method and molecular cloning and a point mutation in the codon 61 (CAA----AAA) was noted. However, examination of the proportion of the mutated N-ras gene in the tumor part by molecular cloning and by hybridization using synthetic oligonucleotide probes indicated that the mutated gene occurred with very low frequency. The activated N-ras gene appears located only in a small fraction of the tumor cells. The experimental data indicate activation of this gene as possibly not the major cause of carcinoma, but rather a manifestation of tumor heterogeneity.
authors.affiliation: Department of Gene Research, Cancer Institute, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Takada
authors.forename: K
authors.initials: K
authors.lastname: Koike
mesh_terms: D000818:Animals; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000209:etiology / Q000235:genetics*; D011905:Genes, ras; D006801:Humans; D008113:Liver Neoplasms / Q000209:etiology / Q000235:genetics*; D051379:Mice; D009154:Mutation; D009693:Nucleic Acid Hybridization; D014162:Transfection