Loss of Wingless or Hedgehog signalling in Drosophila results in the loss of both segment polarity and naked cuticle in the embryonic epidermis. Genetic studies have implicated the glypicans dally and dally-like (dlp), cell-surface heparan sulphate proteoglycans, in Wingless signalling. Now Desbordes and Sanson report that neither glypican is necessary for Wingless signalling in the embryonic epidermis but that Dally-like is required for Hedgehog signalling (see p. 6245). They show that silencing of dally-like but not of dally by RNA interference produces the same segment polarity phenotype as winglessor hedgehog null mutations. In experiments in which they uncouple the normally tightly coupled Hedgehog and Wingless signalling pathways, the researchers reveal a specific requirement for Dally-like in the Hedgehog pathway. Finally, they report that Dally-like is required for reception of the Hedgehog signal, acting upstream or at the level of patched, which encodes the Hedgehog receptor....

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