P2RX4 and ischemic stroke: P2X4 expression in both LPS‐differentiated cultured microglia and acutely isolated microglia from brains of animals 24 hr after ICV injection of LPS was significantly reduced, contrasting findings from our MCAO ischemic stroke microglia and a study using the mouse BV2 microglial cell line (Raouf, Chabot‐Dore, Ase, Blais, & Seguela, 2007).