Fig. 8. Proposed model for neurodegenerative diseases. CaBP-9k KO brain has increased APP/β-amyloid, Tau, and α-synuclein accumulation and endoplasmic reticulum (ER) stress-induced apoptosis. ER stress inhibitor TUDCA restored ER stress- and apoptosis-related gene expression to wild-type levels in CaBP-9k KO mice. Therefore, CaBP-9k may contribute to the onset and progression of neurodegenerative diseases.