title: Amino-acid substitution at codon 13 of the N-ras oncogene in rectal cancer in a Japanese patient.
abstract: The activation of proto-oncogenes in colorectal cancers in Japanese patients was studied using a mouse NIH3T3 cell transfection assay system. Of thirty-five colorectal cancers examined, one rectal cancer showed an unusually high transformation efficiency and, in this rectal cancer, the N-ras oncogene was found to be activated. Nucleotide sequence analysis of the activated N-ras showed a single G----C point mutation at the first letter of codon 13, resulting in the coding of arginine instead of glycine. This amino-acid substitution at codon 13 may be responsible for the efficient induction of transformants of NIH3T3 cells in vitro.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D003062:Codon; D004273:DNA, Neoplasm / Q000235:genetics*; D006801:Humans; D051379:Mice; D009154:Mutation; D009857:Oncogenes; D012004:Rectal Neoplasms / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D003062:Codon; D004273:DNA, Neoplasm