RAB23 is a small GTPase that functions as a key regulator of intracellular membrane trafficking and primary cilium biology. As a member of the Rab family, RAB23 cycles between inactive GDP-bound and active GTP-bound states to regulate vesicle formation, movement, and fusion 1. Its primary developmental role involves negative regulation of Sonic hedgehog (Shh) signaling through cooperation with SUFU to prevent nuclear import of GLI1 transcription factors 2. RAB23 is critical for primary cilium formation and elongation, facilitating localization of G protein-coupled receptors including dopamine receptor DRD1 to cilia 3. Beyond Shh signaling, RAB23 regulates Nodal-mediated left-right patterning and participates in autophagosome assembly for pathogen defense against organisms like S. aureus 4. RAB23 mutations cause Carpenter syndrome, characterized by craniofacial malformations, polysyndactyly, obesity, and intellectual disability 2. The Y79del clinical mutation disrupts the switch II region, impairing binding to interacting partners and causing loss-of-function 5. Paradoxically, RAB23 is upregulated in multiple human cancers including ovarian cancer, bladder cancer, and astrocytoma, where it promotes proliferation, invasion, and epithelial-mesenchymal transition through Shh-Gli1, PI3K-AKT, NF-κB, and Rac1 signaling pathways 678. This dual role as both a developmental regulator and oncogenic driver makes RAB23 a potential therapeutic target.