Probably involved in the organization of the actin cytoskeleton. May act downstream of CDC42 to induce actin filament assembly leading to cell shape changes. Induces pseudopodia formation in fibroblasts. Inhibits MAPK8 independently of CDC42 binding. Controls septin organization and this effect is negatively regulated by CDC42 (By similarity). Interacts with CDC42, in a GTP-dependent manner, and with SEPT7. The CRIB domain mediates interaction with CDC42. Belongs to the BORG/CEP family.