Researchers have shown that the protein COX2 in mouse nerve cells in the central nervous system (CNS) is crucial for hypersensitivity to pain caused by the physical insult associated with inflammation, but not pain caused by the heat associated with inflammation. As pain caused by physical insult is a major symptom of postoperative and arthritic inflammation, it seems that COX2 in nerve cells in the CNS is central to the pain that accompanies these conditions.