The ras oncogenes in aflatoxin B$_{1}$-induced rat liver carcinomas

In summary, the nature of the amino acid changes that impart oncogenicity in either the focus formation or tumorigenicity assay can be inferred by analysis of PCR-amplified DNA from tumor-derived NIH3T3 transformants and confirmed by analysis of primary liver tumors. Putative activating mutations in the c-K-ras genetic locus have been shown to involve a single-base modification of either G-C base pair at codon 12 leading to aspartate or cystein substitutions for glycine. The oncogenicity of an N-ras oncogene containing the N-ras C gene region may be related to an amino acid substitution of valine for glycine at codon 13.