ABSTRACT
ras oncogenes were originally discovered as part of the genomes of highly oncogenic murine retroviruses. At least five sarcoma viruses containing activated versions of ras genes have been isolated (reviewed by Lacal and Tronick 1 ). All these tumors cause sarcomas in rats or mice, the Harvey sarcoma virus and the Kirsten sarcoma virus being the representative isolates carrying the activated forms of H- and K-ras genes, respectively. Thus, the story of ras genes and ras-related genes is linked to animal carcinogenesis. Years later (1982) several groups showed that genes isolated from human tumor cell lines by transfection methods were homologs to the oncogene from Harvey sarcoma virus. This gene was a mutated version from the normal H-ras found in nontumor cells. 2 - 5 Since then, activated ras genes have been found in numerous human and animal tumors.
