Beta-amyloid (Aβ) peptide modulation of neural stem cell (NSC) self-renewal is prion protein (PrP) dependent. (A) Representative images of NSC colonies grown in a collagen matrix with or without Aβ for 21 days. (B) Neurosphere volume of untreated knock-out (KO) and wild-type (WT) cells. (C) Neurosphere volume following Aβ treatment calculated from colony diameter (D) and number (E). (F) Flow cytometry cell cycle phase analysis by DNA content; an example experiment from four repeats is shown. Scale bars = 100 μm. Data are represented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001.