||WASP (for Wiskott-Aldrich syndrome protein) and N-WASP are downstream effectors of Cdc42 that are implicated in actin polymerization and cytoskeletal organization. The WASP family also includes VASP (vasodilator-stimulated phosphoprotein) and Mena (for mammalian enabled protein， which accumulate at focal adhesions and are also involved in the regulation of the actin cytoskeleton. The WAVE proteins are related to the WASP family proteins and are likewise involved in mediating actin reorganization downstream of the Rho family of small GTPases. The two protein homologs WAVE1 and WAVE2 specifically regulate membrane ruffling by inducing the formation of actin filament clusters in response to GTP binding and activating Rac. The WAVE proteins mediate this actin polymerization by cooperating with the Arp2/3 complex, a nucleation core, and thereby promoting the formation of actin filaments. WAVE1, which is also designated SCAR (for suppressor of cAR， is expressed primarily in the brain, while WAVE2 is widely expressed with the expression highest in peripheral blood leukocytes. WAVE3 forms a multiprotein complex that links receptor kinases and actin. Binding to actin occurs through a C-terminal verprolin homology domain in all family members. The multiprotein complex serves to tranduce signals that involve changes in cell shape, motility or function.