Of particular interest, the Wnt family (Lie et al., 2005; Sato et al., 2004), β-catenin (Chenn and Walsh, 2003; Shimizu et al., 2008) and notch -1 were identified as critical regulators of neurogenensis in the adult brain [Figure 1, For review see (Shi et al., 2008)]. Wnts are made and secreted by astrocytes in the adult hippocampal niche and specifically increase proliferating neuronally-restricted precursor proliferation and differentiation (Lie et al., 2005). Wnt has also been implicated in neurogenesis originating from the SVZ during stroke repair (Morris et al., 2007; Lei et al., 2008). It was suggested that in the adult brain, notch signaling modulates cell cycle time thus enabling self-renewal of NSC (Alexson et al., 2006). Interestingly, Shimizu and colleagues (2008) provide evidence suggesting that glycogen synthase kinase 3 (GSK3) inactivation and β-catenin stabilization by Wnts are essential for the self-renewal of neural stem cells. Noteworthy are the findings that β-catenin promotes neural precursor cell proliferation through the activation of LEF/TCF transcription factors. Interestingly, nuclear accumulated β-catenin also induces antineurogenic hes1 gene expression through the enhancement of Notch1- and RBP-J
