N-Formyl-Met-Ala-Ser Peptide (fMet-Ala-Ser) binds to formyl peptide receptors on neutrophils. N-Formylmethionine-containing peptides including the most potent and known member, N-formyl-Met-Leu-Phe (FMLP or fMet-Leu-Phe) stimulate human neutrophils by a receptor-dependent mechanism. These peptides are important chemotatic factors and theirs receptors are important chemotatic factor receptors (FPR or formyl peptide receptors: FPR1, FPR2 and FPR3) that act respectively as signaling and signal-recognizing elements to initiate the inflammation response in order to defend the body against bacterial invasion.For-Met-Ala-Ser-OH or For-MAS-OH