CDK5 and Alzheimer disease: For example, XBP1 activates the expression of AD-related genes such as those encoding for subunits of the γ-secretase complex or cyclin-dependent kinase 5 (CDK5) (Acosta-Alvear et al., 2007) and can influence amyloid precursor protein (APP) processing (Yang et al., 1998; Domingues et al., 2007).