Medulloblastoma, PNET and neuroblastoma primary tumours express high levels of COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1), the two enzymes responsible for converting arachidonic acid, a dietary fatty acid and precursor to eicosanoid synthesis, to prostaglandin E2. The gene discussed is PTGES; the disease is medulloblastoma.