Cell-permeable. A potent, selective, reversible and non-competitive inhibitor of Cdc42 GTPase (IC₅₀ = 2.6 and 5.4 μM for Cdc42 wild type and activated mutant, respectively). No appreciable inhibitory activity up to 100 μM was observed with Rac1, Rab2, Rab7 or Ras in the multiplex screen.