Originally identified as factors affecting Drosophila embryogenesis, the Hedgehog (Hh)
pathway is one of the primary signaling systems that specify patterns of cell growth and
differentiation during vertebrate development. Mutations in various components of this
pathway frequently occur in tumors originated from the skin, cerebellum, and skeletal
muscle, and abnormal pathway activity is associated with a subset of lung, digestive tract,
pancreatic, and prostate cancers. Because of these potent biological activities, this pathway …