Furthermore, the possibility to separate cells with different rates of APP processing, i.e., different red/green ratios, using the cell-sorting capability of FACS might allow to perform a complete proteomic, lipidomic and transcriptomic analysis of these sub-populations of cells, and to address one of the most puzzling questions in the context of Alzheimer’s disease: why the proteolytic processing of APP is higher in certain cells than in others. This evidence concerns the gene APP and early-onset autosomal dominant Alzheimer disease.