MAP6D1 (MAP6 domain containing 1) is a microtubule-associated protein with diverse cellular functions beyond canonical microtubule stabilization. Primary function: MAP6D1 stabilizes microtubules and assembles ciliary doublet microtubules by recruiting tubulin dimers onto the A-tubule lattice to initiate B-tubule nucleation, with its loss resulting in shortened cilia characteristic of ciliopathies 1. Mechanism: The protein localizes to multiple subcellular compartments including the Golgi apparatus, plasma membrane, mitochondria (at the outer membrane and intermembrane space), and primary cilia via its Mn-motif domain 21. MAP6D1 undergoes N-terminal palmitoylation by DHHC-type enzymes and can multimerize via its microtubule-binding module 2. It also promotes formation of luminal protofilaments in microtubules, enhancing stability 1. Disease relevance: MAP6D1 has been identified in multiple disease contexts. DNA methylation changes in MAP6D1 occur following maternal antenatal corticosteroid exposure in neonates, implicating it in neurodevelopmental pathways 3. The gene shows altered expression in clear cell renal cell carcinoma progression and serves as a stage-classification biomarker 4. MAP6D1 is targeted by WTAP in multiple myeloma progression via Hippo pathway modulation 5, and elevated expression correlates with gestational diabetes mellitus pathogenesis 6. Clinical significance: MAP6D1 is associated with lymph node metastasis prediction in prostate cancer 7 and liver cancer progression through HNF4α-regulated enhancer interactions 8.