Members of the Hedgehog (Hh) family of secreted signaling molecules direct an enormous
variety of developmental events in vertebrates and in Drosophila. To fulfill these roles, both
the distribution of Hh molecules and the response of cells to Hh must be tightly regulated. A
good deal is known about the mechanisms that determine which cells make Hh in
Drosophila, and some fascinating observations are prompting ideas about how Hh is
transported between cells (