Mutational activation of H-ras and K-ras genes is absent in N-nitroso-N-methylurea-induced liver tumors in rats.

We examined mutational activation of H- and K-ras genes in hyperplastic nodules and hepatocellular carcinomas induced by N-nitroso-N-methylurea or diethylnitrosamine using the polymerase chain reaction, followed by dot-blot hybridization. No mutational activation was detected in these hepatic lesions. The results indicate that low incidence of the activation of H- and K-ras genes in rat liver tumors is due to the organ specificity rather than the nature of the carcinogens used.

N‐nitroso‐N‐methylurea

diethylnitrosamine

glutathione‐S‐transferase placental form

polymerase chain reaction