Figure 1. PrP is expressed in neural stem cells and modulates self-renewal and proliferation. (A) Representative images depicting immunofluorescent staining in neurospheres derived from PrP-expressing mice and cultured over laminin for 24h. Staining with specific antibodies was performed to detect GFAP (astrocytes, green) and PrP (red), and the nuclei were stained with DAPI (blue). (B) Scheme showing that neurosphere formation is increased in wild-type (Prnp^+/+) cells in the presence of STI1, but is impaired in PrP-null (Prnp^−/−) cells. Note that the signaling pathways triggered by PrP-STI1 engagement during proliferation and self-renewal processes (detailed in the inset), as well as the role of the PrP-STI1 complex in the classical differentiation of NSC, require further investigation.