RAB23, also known as ras-related protein Rab23, is a member of the Rab family of proteins and localizes to the cytoplasmic side of the cell membrane. This protein is thought to to play a role in intracellular protein transportation and signal transduction mediated by small GTPases. RAB23 is an essential negative regulator of the Sonic hedgehog signaling pathway. Mutations in the gene encoding RAB23 may result in Carpenter syndrome a condition characterized by obesity, cardiac defects, polysyndactyly and craniosynostosis.