Hedgehog and its circuitous journey from producing to target cells.

The hedgehog (Hh) signaling protein has essential roles in the growth, development and regulation of many vertebrate and invertebrate organs. The processes that make Hh and prepare it for release from producing cells and that move it to target cells are both diverse and complex. This article reviews the essential features of these processes and highlights recent work that provides a novel framework to understand how these processes contribute to an integrated pathway.