This annexin/lipocortin-1 peptidomimetic (FW = 1351.58 g/mol; Sequence: Acetyl-AMVSEFLKQAW; CAS 256447-08-2; Soluble to 1 mg/mL in 20% (vol/vol) acetonitrile-H2O) markedly reduces the degree of neutrophil adhesion and emigration across mouse mesenteric postcapillary venules, when administered at 13 mg/kg (s.c.), but does not modify cell rolling, when assessed directly by intravital microscopy. Ac2-12 also promotes neutrophil detachment from mesenteric endothelium after activation by intraperitoneal injection of 1 mg zymosan in mice (i.e., zymosan peritonitis). Ac2-12 phenocopies the effects observed in FormylatedPeptide Receptor (FPR) knock-out mice.