Sema3A-mediated dissociation of FARP2 from Plexin-A is followed by activation of Rac1 by the GEF activity of released FARP2.<br>FARP2 is critical for Sema3A-mediated axonal repulsion through two independent downstream signaling pathways. Sema3A mediated disassociation of FARP2 from Plexin-A is followed by activation of Rac by GEF activity of released FARP2, binding of Rnd1 to plexin-A and down regulation of R-Ras by GAP activity of plexin-A.