Wnt signalling: variety at the core.

The Wnt/beta-catenin pathway is a conserved cell-cell signalling mechanism in animals that regulates gene expression via TCF/LEF DNA-binding factors to coordinate many cellular processes. Vertebrates normally have four Tcf/Lef genes, which, through alternative splicing and alternative promoter use give rise to a variety of TCF/LEF isoforms. Recent evidence from several experimental systems suggests that this diversity of TCF/LEF factors is functionally important in vertebrates for mediating tissue- and stage-specific Wnt regulation in embryonic development, stem cell differentiation and associated diseases, such as cancer.