ML 141 is a potent, selective inhibitor of the Rho family GTPase cdc42. The IC50 for inhibition of enzymatic activity is 200 nM, with no activity against Rho family members Rac, Ras or Rab. Cdc42 has been implicated in the regulation of actin polymerization through its direct binding to Neural Wiskott-Aldrich syndrome protein (N-WASP), which subsequently activates Arp2/3 complex. This complex mediates the polymerization of actin into branched networks and regulates important functions including cell adhesion, cytoskeletal arrangement, phagocytosis and host-pathogen interactions, motility, migration, and membrane protein trafficking.