Sortilin delivers Aβ to lysosomes. A, Replicate layers of CHO–mSort cells were incubated with HiLyte–Aβ40 complexed with lipidated APOE4 for 1 h. Subsequently, the subcellular localization of sortilin, APOE4, and Aβ40 was documented by immunofluorescence microscopy. B, Immunocytochemical detection of HiLyte–Aβ40 and lysosomal marker cathepsin B in CHO–mSort. The inset depicts the merged micrographs. Scale bars, 4 μm.