of oncogenes that encode for GTPases (enzymes
located at the plasma membrane
or in the cytoplasm). They were first identified as the transforming genes
in the Harvey sarcoma
virus (H- or Ha-ras) and the Kirsten sarcoma
virus (K- or Ki-ras).
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.