CTSD and Alzheimer disease: NCL10- and AD-associated CTSD variants were overexpressed in SH-SY5Y cells deficient for CTSD (CTSD KO) and immunoblot analyses were performed to analyze protein expression, stability as well as CTSD maturation: pro- (∼52 kDa) and intermediate form (∼48 kDa) were analyzed together as immature CTSD (Figure 1C).