XBP1 and Parkinson disease: We showed that miR-34a-5p, which is upregulated in the brains of Alzheimer’s and Parkinson’s disease patients, directly targets the genes BIP (binding immunoglobulin protein), IRE1α (inositol-requiring enzyme 1 α), and XBP1 (X-box binding protein 1), all of which are part of the IRE1α branch of the UPR.