XBP1 and infection: For instance, it has been documented that infection by the Hepacivirus hepatitis C virus (HCV) leads to the activation of the three UPR signaling pathways (Shinohara et al., 2013) including BiP expression, IRE1 activation, and Xbp-1 splicing (Tardif et al., 2004), ATF6 cleavage (Tardif et al., 2002; Li et al., 2009), eIF2α phosphorylation, and induction of CHOP expression (Chan and Egan, 2005).