Compounds which inhibit the small G protein Rho GTPase cell division cycle protein Cdc42 are provided. Morphological analyzes of filopodia, western blots of Ccd42 phosphorylation, and effects on cellular wound healing and on growth cone formation all demonstrate that the described compounds are able to inhibit all tested Cdc42-mediated processes. The compounds effectively inhibit the effects of Cdc42 and effectively inhibit Cdc42-related cellular functions involving actin, such as Golgi organization and cell movement. Furthermore, the described Cdc42 inhibitor compounds may be provided as a medicament for the treatment of various conditions.