APP and Alzheimer disease: However, using the APPswe/PS1ΔE9 transgenic mouse model (APP/PS1), a classical model of Alzheimer’s disease expressing human APPswe that can readily be cleaved into Aβ in the hippocampus and cortex of mice [15], we were not able to detect Aβ monomers in retinal lysates at 5.5, 6 and 13 months of life [8].