Related RAS Viral Oncogene Homolog 2 (RRAS2)

The TC21 oncogene, a member of the RAS superfamily, was initially cloned from a human teratocarcinoma cDNA library by PCR methods using degenerate oligonucleotides corresponding to the conserved region of the RAS genes. Chan et al. (1994) found the same oncogene when they generated an expression cDNA library from an ovarian carcinoma line. They found, furthermore, that a single point mutation substituting glutamine for leucine at position 72 was responsible for activation of transforming properties. While the cDNA clone possessed high transforming activity, the ovarian tumor genomic DNA, which contained the mutated TC21 allele, failed to induce transformed foci. Thus, expression cDNA cloning made it possible to identify and isolate a human oncogene that had evaded detection by conventional approaches.