Compound 1 has been shown to be a dual prenylation inhibitor with FPTase (IC50=2 nM) and GGPTase-I (IC50=95 nM). Analogues of 1, which replaced the cyanophenyl group with various biaryls, led to the discovery of highly potent dual FPTase/GGPTase-I inhibitors. 4-trifluoromethylphenyl, trifluoropentynyl, and trifluoropentyl were identified as good p-cyano replacements.