In agreement with these observations, another study showed an increase in the amount of several proteins implicated in the UPR (phosphorylated eukaryotic initiation factor 2 (eIF2α-P), chaperone GRP78, XBP1 and CHOP) in leucocytes treated with tunicamycin from controls but not in those from BD patients (Pfaffenseller et al., 2014). Here, XBP1 is linked to Behcet disease.