As RAS oncoproteins play a major role in human malignancy, inhibiting RAS function is a promising approach for developing anticancer therapies. Among these approaches are agents such as farnesyltransferase inhibitors (FTIs) and the nontoxic farnesylcysteine analogue farnesylthiosalicylic acid (FTS) that dislodges all RAS isoforms from the membrane, as well as methods to restore regulation of RAS-GTP levels and to alter the interaction of RAS-GTP with downstream targets.