Dynamic regulation of the actin cytoskeleton underpins a multitude of cellular processes, from cell movement and polarization1,2 to cell division.3 The actin cytoskeleton and the proteins involved in its regulation are also fundamentally linked to endocytosis and membrane trafficking.4,5 Members of the Rho family of small GTPases have emerged as important overseers of the actin cytoskeleton and a number of Rho family members and their downstream effector proteins have been linked to specific actin pathways. Among the Rho family ...