APP and Alzheimer disease: We used an aging model to study the spontaneous accumulation of Aβ protein aggregates (mimicking the sporadic form of AD) in HIF-P4H-2-deficient mice and a transgenic mouse model overexpressing amyloidogenic human APP and PSEN1 variants (APP/PSEN1) subjected to sustained environmental hypoxia (15% O2 for 6 weeks) at two age points, 4 and 10 months.