SMO and Keratocystic odontogenic tumor: Without Shh ligand, Ptch plays a regulatory role by inhibiting the Smo protein.398 Ptch protein silencing or gene deletion is related to the development of many cancers, such as odontogenic keratocyst, BCC and plexiform fibromyxoma.213,399,400 Therefore, activators targeting Ptch can prevent cancer development by inhibiting Smo protein.