APP and neuroblastoma: The present study comprises a comprehensive in vitro analysis of APP, α- β- and γ-secretase expression and levels, and β- and γ-secretase activities, all measured in a human neuroblastoma cell line (SK-N-BE); most importantly, the cells were first differentiated toward a neuronal phenotype, by treatment with all-trans-retinoic acid, then challenged with ‘patho-physiological amounts’ of 24-OH or 27-OH.