ATF4 and Parkinson disease: To determine how PD linked DJ-1 mutations affect ATF4 protein expression under basal and ER stress conditions, we infected cortical neurons and SH-SY5Y+ cells with recombinant-adenovirus-expressing Flag-DJ-1 WT, Flag-DJ-1 L166P, or pcDNA3 (empty vector) as a control for 30 h following infection.