Annexin 1 is an anti-inflammatory protein that plays a key role in innate immunity by
modulating the activation of several types of cells, including neutrophils. Here we have
developed a cleavage assay using tagged annexin 1 and observed marked activity in the
membrane fraction of activated neutrophils. A combination of inhibitors, transfected cells,
and proteomic analyses allowed us to identify proteinase 3 as the main enzyme responsible
for this cleavage in the N terminus region of the protein, at least in the context of neutrophil …