A number of proteins and low-molecular weight compounds have been reported to suppress the activity toward ras-oncogenes and their products. These include anti-lias antibody, inhibitors of Ras activation, Ras dominant negative mutants, inhibitors of processing of newly-synthesized Ras, suppressors and inhibitors of downstream effecters and genetic probes such as anti-sense oligonucleotides and ribozymes. There are also other Ras inhibitors whose action mechanisms remain to be proved. Some of these inhibitors might be useful as cancer therapeutic agents.