Activation of c-ras oncogenes by mutations and amplification.

About 15% of all human tumours, including carcinomas, sarcomas, melanomas and leukaemias, contain c-ras oncogenes, which can be detected by a variety of methods. The activating lesion in the c-ras oncogenes is most often a point mutation affecting certain critical amino acid residues of its protein product. The clinical significance of c-ras oncogenes is not yet clear.