CCDC66 is a microtubule-associated protein with essential roles in ciliogenesis and cell division. Primary function involves regulating primary cilium assembly, length, and stability through microtubule stabilization 1. CCDC66 localizes dynamically to centrosomes, centriolar satellites, transition zones, and ciliary axonemes 2, mediating protein trafficking to these compartments 3. The protein cooperates with ciliopathy-linked factors CEP104 and CSPP1 to regulate transition zone assembly and IFT-B complex recruitment, controlling both cilium structure and Hedgehog signaling 2. During cell division, CCDC66 functions in mitotic progression by regulating spindle assembly, kinetochore-fiber integrity, and chromosome 3; and in cytokinesis through central spindle and midbody organization 4. This dual functionality involves microtubule nucleation via gamma-tubulin recruitment and microtubule bundling through its C-terminal domain 4. Disease relevance includes ciliopathies such as Joubert syndrome, where CCDC66 dysfunction causes shortened cilia with impaired axonemal modifications and aberrant ciliary stability 5. Additionally, circulating CCDC66 shows diagnostic potential as a colorectal cancer biomarker 6. These multifaceted roles establish CCDC66 as a critical regulator integrating ciliary and mitotic microtubule dynamics.