Making a vertebrate limb: new players enter from the wings.

What initiates vertebrate limb development and induces limbs to form where they do? For several years the answer to this intriguing question has been framed in terms of a working model that limb induction depends on a dialogue between two members of the Fibroblast Growth Factor (FGF) family of intercellular signaling molecules, FGF8 and FGF10. Now, a recent paper has written roles for signals encoded by WNT genes, the vertebrate relatives of the Drosophila wingless gene, into the script. Copyright 2001 John Wiley & Sons, Inc.