Hedgehog signaling

A conserved regulatory cascade that is important in vertebrates and Drosophila for patterning and cell proliferation during development. The main components in this pathway are Hedgehog (Hh), mammalian Sonic hedgehog (Shh), skinny hedgehog (Ski), dispatched (Disp), patched (Ptch), and Smoothened (Smo). C. elegans lacks true Hh and Smo orthologs; however, it does have orthologs of Ski, Disp, and Ptch along with multiple hegdgehog-related (Hh-r), Patched (PTC) and patched-related (PTR) genes.