SIGNAL-TRANSDUCTION BY THE WNT FAMILY OF LIGANDS

The Wnt genes encode a large family of secreted polypeptides that medi ate cell-cell communication in diverse developmental processes. The lo ss or inappropriate activation of Wnt expression has been shown to alt er cell fate, morphogenesis and mitogenesis. Recent progress has ident ified Wnt receptors and components of an intracellular signalling path way that mediate Wnt-dependent transcription. This review will highlig ht this 'core' Wnt signal-transduction pathway, but also aims to revea l the potential diversity of Wnt signalling targets. Particular attent ion will be paid to the overlap between developmental biology and onco genesis, since recent progress shows Wnt signalling forms a paradigm f or an interdisciplinary approach.