APOE and Alzheimer disease: In addition to our observation of an enrichment in differentially expressed endosomal–lysosomal genes, our transcriptomics analysis revealed many other intriguing genes that were found to be differentially expressed in the EC of aged APOE3/4 vs. APOE3/3 mice, which we hope will spur additional research on the possible effects of these genes in APOE4-associated AD pathogenesis.