HERPUD1 and Alzheimer disease: Although Aβ-S8C stimulation upregulates ATF3 and DDIT3 (CHOP) in both CON and AD neuronal cultures, the prominent alteration in the UPR was observed in the AD TREM2 cultures with the upregulation of XBP1, ATF4, BBC3, HERPUD1 and CALR. In support of our data, several studies have shown upregulation of the UPR in brain samples of AD patients [84,85].