Release and trafficking of lipid-linked morphogens.

Wnt and Hedgehog family proteins are secreted morphogens that act on surrounding cells to pattern many different tissues in both vertebrates and invertebrates. The discovery that these proteins are covalently linked to lipids has raised the puzzling problem of how they come to be released from cells and move through tissue. A synergistic combination of biochemical, cell biological and genetic approaches over the past several years is beginning to illuminate both the forms in which lipid-linked morphogens are released from cells and the variety of molecular and cell biological mechanisms that control their dispersal.