[Joint amplification of c-myc and c-Ha-ras oncogenes in human breast and thyroid cancer cells].

Both c-myc and c-Ha-ras 1 oncogenes amplification and enhanced expression were revealed in some human mammary and thyroid carcinomas by the molecular genetic analysis. Amplification proves to be a second possible molecular mechanism of the ras family protooncogene activation besides a point mutation. The coexistence of c-myc and c-Ha-ras 1 in some human primary carcinomas suggests a multistep process of carcinogenesis.