To further characterize whether the altered distribution of retromer components in NPC1-null cells has functional consequences, we analyzed the colocalization of Vps35 and APP (Figure 3), a key Alzheimer’s protein that is transported out of early endosomes via retromers—a process that protects against Aβ formation and Alzheimer’s disease. Here, NPC1 is linked to early-onset autosomal dominant Alzheimer disease.