Figure 1.

Putative role of β-catenin in stem-cell renewal and maintenance through cadherin-containing adherens junctions and Wnt signalling. Support cells such as CAP cells, inner sheath cells or spindle-shaped N-cadherin⁺CD45⁻ osteoblastic (SNO) cells form adherens junctions with germline stem cells, somatic stem cells or haematopoietic stem cells (HSCs), respectively, through E-cadherin or N-cadherin and β-catenin (Lin, 2002). In addition, β-catenin can be stabilized as a result of Wnt signalling through the frizzled (Fzd) receptors leading to the inhibition of the APC–axin–GSK3-β complex, allowing transcriptional activation of target genes by T-cell factor (TCF)/β-catenin complexes.