Upregulation of IRE1, PERK, eIF2α, and ATF4 in PD cell models (Ryu et al., 2002).Phosphorylated PERK and phosphorylated eIF2α detected in dopaminergic neurons of PD patients (Hoozemans et al., 2007).Co-localization of phosphorylated PERK and α-synuclein in dopaminergic neurons (Hoozemans et al., 2007).CHOP upregulation in dopaminergic neurons of mouse models and in cell models (Ryu et al., 2002; Holtz and O'Malley, 2003; Silva et al., 2005). Here, ATF4 is linked to Parkinson disease.