Results showed that the changes in oxysterol levels in ApoE4 astrocytes somehow reflect some of those occurring in the AD brain (i.e., 24-OHC decrease, 27-OHC and 25-OHC increase) [19]; in fact, it should be considered that other ApoE4 cell types (i.e., neurons, microglia) could differently contribute to the brain oxysterol content, as well as other systemic and/or environmental factors, among which oxidative stress. This evidence concerns the gene APOE and Alzheimer disease.