 Following cell activation (for example, by neutrophil adhesion to endothelial-cell monolayers), annexin A1 is promptly mobilized to the cell surface and secreted.Annexin A1 promotes neutrophil detachment and apoptosis, and phagocytosis of apoptotic neutrophils by macrophages.On the other hand, it reduces the tendency of neutrophils to penetrate the endothelium of blood vessels.