since the earliest results on the linkage between ras activation and cell transformation appeared a vast amount of additional information has been generated which emphasizes the importance of ras-related genes in membrane trafficking, cell proliferation, differentiation and cancer. These advances led to the development of new strategies for the diagnosis, prognosis and prevention of cancer. Ras-related genes appear to be central to the mechanism of transformation by other oncogenes and therefore constitute a focal point upon which attempts to intervene in the process of carcinogenesis will be...