APP and Alzheimer disease: In hippocampal slice cultures at DIV9, transient expression of a familial AD APP mutation (APPSwedish) (Mullan et al., 1992) with GFP in CA1 pyramidal neurons for 6 days did not reduce their dendritic spine densities compared with neurons expressing GFP alone (Figure 1A and B), suggesting that APP alone does not significantly contribute to synaptic loss.