The Wiskott–Aldrich syndrome protein (WASP) family proteins. WASP family proteins consist of multiple functional domains. WASP and neural WASP (N‐WASP) are activated by direct binding to Cdc42 via the CRIB domain, whereas WAVE (WASP‐family verprolin‐homologous proteins) bind to Rac indirectly via various molecules. The C‐terminal verprolin‐homology, cofilin‐like, and acidic (VCA) domains are important for the induction of actin polymerization. The V and CA domains bind actin monomer (G‐actin) and the Arp2/3 complex, respectively. WASP family proteins activated by Rac and Cdc42 induce Arp2/3 complex‐dependent actin polymerization via the VCA domain. B, basic; CA, cofilin‐like and acidic; CRIB, Cdc42 and Rac interactive binding; IQ, IQ motif; Pro‐r, Proline‐rich; V, verprolin homology; WH1, WASP homology 1; WHD, WAVE homology domain.