CDNF and hemorrhagic stroke: In our study, rhCDNF treatment was shown to suppress the PERK-ATF4-CHOP pathway, accompanied by decreasing phosphorylation of GSK-3β at Tyr216 and increasing nuclear Nrf2 levels, suggesting that CDNF may play a pivotal role in regulating PERK downstream branches in the cellular outcome of ER stress after the hemorrhagic stroke.