ABO and Alzheimer disease: Interestingly, AβO labeling appeared to be intra- and extracellular as measured by the anti-oligomer NU4 antibody, which does not recognize monomeric Aβ (Forny-Germano et al., 2014, their Figure 2); however, data using APP transgenic mice expressing the E693Δ mutation, which increases Aβ oligomerization without fibrillization, found that intraneuronal AβOs alone were sufficient to induce features of AD pathology (Tomiyama et al., 2010).