PTGS2 and myeloid sarcoma: P2X7R immunoreactivity is augmented also in activated microglia/macrophages in spinal cord during MS, and extracellular ATP apparently contributes to MS lesion-associated release of interleukin-1β from microglia/macrophages, via P2X7R-dependent induction of cyclooxygenase-2 and downstream pathogenic mediators (21).