CASP4 and Parkinson disease: In view of the significant investigation of ER stress signaling in PD pathogenesis [4,7,9,11,12], further study was expanded to assess the effect of UBA52 on ER stress-related signaling factors such as GRP78, GADD153, cleaved caspase-4 (human analog of caspase-12) in control and Myc-UBA52 transfected cells upon PD induction.