187-1, N-WASP inhibitor, a 14-aa cyclic peptide, is an allosteric neural Wiskott-Aldrich syndrome protein (N-WASP) inhibitor. 187-1, N-WASP inhibitor potently inhibits actin assembly induced by phosphatidylinositol 4,5-bisphosphate (PIP2) with an IC50 of 2 μM. 187-1, N-WASP inhibitor prevents the activation of Arp2/3 complex by N-WASP by stabilizing the autoinhibited state of the protein.