GPR17 and brain ischemia: Interestingly, GPR17 expression is increased after traumatic brain injury in patients,8 after brain ischemia in mice4 and in several animal models of CNS injury.5, 9, 10, 11 However, the process underlying the accumulation of GPR17+ cells at the site of ischemic lesions,4, 12 the rate and kinetics of their maturation and their final fate are still largely unknown.