PTGS1 and Alzheimer disease: COX‐1, expressed in microglia, is upregulated in AD and leads to increased synthesis of prostaglandin E2, thereby leading to initiation and propagation of inflammation.[28] COX‐2, largely expressed in neurons, is central to excitotoxic death.[29, 30] Aging mice had significantly increased microglial COX‐1 expression compared to young mice, which was no longer significant with iMP treatment (Figure S3K,L, Supporting Information).