To study the impact of GRINA deficiency and EPO administration on the activation of the IRE1α and PERK branches of the UPR in a time-dependent manner after ischemic stroke, we used biopsies from the peri-infarct zones and the corresponding contralateral hemisphere of both genotypes after 6 and 72 h of reperfusion for gene expression analyses. The gene discussed is ERN1; the disease is ischemic stroke.