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Nature Reviews Molecular Cell Biology 4, 321–325 (1 April 2003) | doi:10.1038/nrm1078

Wnts as morphogens? The view from the wing of Drosophila

Alfonso Martinez Arias

Morphogens are diffusible signalling molecules that pattern cellular fields by setting up differential gene expression in a concentration-dependent manner. Members of the Wnt family of signalling molecules are generally considered to be classical morphogens. However, a close analysis of their activity indicates that they do not fulfil all of the critera that are associated with the classical definition.