“…Ptch1 has a sterol sensing domain (SSD) and a large nonstructured intracellular domain like the Niemann Pick C1 protein (NPC1). It belongs to the Resistance-Nodulation-Division (RND) superfamily which also includes efflux pumps mostly of bacterial origin [37]. RND transporters can extrude a wide variety of substrates such as sterols, lipids, bile salts, fatty acids, and metal ions, as well as lipophilic drugs, and are involved in drug resistance [38].…”