ARL13B is a cilium-localized regulatory GTPase essential for primary cilium formation and function 1. It controls ciliary protein trafficking and membrane composition by regulating intraflagellar transport (IFT) subcomplexes and recruitment of cargo-binding proteins 2. In neural development, ARL13B is required for cerebral cortex patterning, including radial glial scaffold formation and interneuron migration 3. The protein regulates Hedgehog signaling by controlling Smoothened (SMO) and GLI localization within cilia, independent of exogenous ligand 4. Additionally, ARL13B mediates ciliary trafficking of phosphatidylinositol phosphatase INPP5E, crucial for ciliary signaling 2. Beyond development, ARL13B promotes tumor angiogenesis by activating VEGFA-VEGFR2 signaling in endothelial cells and regulates glioma growth through Hedgehog pathway activation 5. In stress responses, the ARL13B-ARL3 GTPase cascade regulates senescence initiation through cilia-to-PML-nuclear body communication 6. ARL13B dysfunction associates with Joubert syndrome 8 7, while its roles extend to male reproductive physiology in both motile and primary cilia contexts 8.