Related genes constitute a multi-gene family with numerous roles in vertebrate development.
Other studies suggest potential roles of vertebrate hh proteins in the development of skin, teeth, gut, bladder, bone and testis. The aberrant activation of the hh signaling pathway also has been implicated in the formation of basal cell carcinoma, the most common form of human cancer, as well as several other types of tumors. The hh family of signaling proteins thus have emerged as important regulators of animal cell proliferation and differentiation. All Hh proteins undergo an intramolecular autoprocessing reaction mediated by the carboxy-terminal domain of the protein. In addition to internal cleavage, this reaction involves attachment of a cholesterol adduct to the amino-terminal product of cleavage, which is the portion of the protein responsible for all known biological signaling activity.