APOE and Alzheimer disease: We further propose that the intermolecular disulfide bridges present in ApoE2 multimers (Fig 2A) and ApoE3 dimers (Fig 2B) decrease AD risk specifically by concealing and protecting vulnerable lipid cargo transported by ApoE-containing lipoproteins from peroxidation, thus preventing the deleterious downstream consequences of lipoprotein peroxidation (reviewed in [15]).