Soluble amyloid precursor protein alpha (sAPPα) acts on both neural stem cells and neural progenitor cells to enhance proliferation. Singly dissociated cells derived from the neurosphere formation assay described in Figure 1 were immunostained for DAPI (a), Sox2 (b), and Sox2/nestin (c,e). GM6001 (GM) not only reduced total cell number but significantly reduced populations of Sox2 and Sox2/nestin-expressing cells. sAPPα rescued the total cell number by enhancing the proliferation of these populations (c). Representative images of Sox2/nestin double-labeling are shown (e). (d) The effect of GM6001 on neural stem cell self-renewal. Primary neurospheres were dissociated, and a single cell per well was cultured in a 96-well plate in the presence of NC, GM, or GM + sAPPα. The percentage of single cells that formed secondary neurospheres is shown. Scale bars = 85 μm (upper panel), 50 μm (lower panel). (f) Representative images of neurosphere formation assay showing the effect of varying concentrations of sAPPα on the size of GM6001-treated neurospheres. Error bars represent standard error of the mean. *P < 0.05, analysis of variance with post hoc analysis. DAPI, 4'-6-diamidino-2-phenylindole.