APOE and Alzheimer disease: We found that APOE ε4 induction at the amyloid-seeding stage dramatically increased the accumulation of Aβ oligomers in AD iNs harboring PSEN1 mutation, relative to AD iNs with APOE ε4 induction after the amyloid-seeding stage (Fig. 2d, Additional file 1: Fig. S5c).