P2RX4 and stroke disorder: Furthermore, the upregulation of microglial P2X4R expression has also been reported in animal models of stroke (Cavaliere et al., 2003), brain tumor (Guo et al., 2004), traumatic brain injury (Guo and Schluesener, 2005; Zhang et al., 2007), spinal cord injury (Schwab et al., 2005), epilepsy (Ulmann et al., 2013), and in human acute inflammatory demyelinating polyradiculoneuropathy (Zhang et al., 2008).