PTGS2 and ischemic stroke: To examine whether COX-2 deficiency affects neutrophil infiltration in ischemic stroke, levels of myeloperoxidase (MPO, an indicator of neutrophil infiltration into the brain parenchyma), neutrophil elastase (NE), and lipocalin-2 (LCN2, also known as neutrophil gelatinase-associated lipocalin) were measured in cortical homogenates of COX-2+/+ and COX-2−/− mice at 24 h after MCAO.