Antagonist of formyl peptide receptor-like 1 (FPRL1) signalling. WRW4 inhibits WKYMVm binding to FPRL1 (IC₅₀ 0.23 mM) as well as the intracellular calcium release induced by WKYMVm, MMK-1, amyloid β42, and F peptide. The tryptophan-rich peptide also inhibits FPRL1-mediated signalling in human neutrophils and blocks chemotactic migration and superoxide generation by Aβ42. WRW4 inhibited the activation of FPRL2 by F2L, an FPRL2-selective endogenous agonist, resulting in the complete inhibition of intracellular calcium increase and chemotactic migration.