Rho GTPases act as molecular switches to regulate the cytoskeletal dynamics underlying cell motility.  Rho GEFs (guanine nucleotide exchange factors) positively regulate Rho GTPases by accelerating GDP dissociation and allowing formation of the active GTPase-GTP complex. Active Rho GTPases typically stimulate cell growth and migration, sometimes triggering tumorigenesis or invasion. Selectively disrupting GEF action using