FAM110A (family with sequence similarity 110 member A) is a cell cycle-regulated protein that functions as a critical regulator of mitotic spindle assembly and chr20 segregation. Structurally, FAM110A localizes to centrosomes and spindle poles during mitosis 1, with its N-terminal domain binding actin and C-terminal domain binding tubulin 2. Mechanistically, casein kinase 1 (CK1) phosphorylates FAM110A at serine residues 252-255, promoting its enrichment at spindle poles and enabling it to bridge microtubules with the actin cytoskeleton to ensure proper spindle formation and chr20 alignment 32. Depletion of FAM110A impairs F-actin assembly at spindle poles and delays metaphase-to-anaphase transition 3. Beyond mitosis, FAM110A serves as a prognostic and immunological biomarker across multiple cancers, particularly hepatocellular carcinoma, where it correlates with immune checkpoint gene expression and infiltration of immune cells 4. In colorectal cancer, FAM110A functions as a mast cell marker associated with immunosuppressive phenotypes and enhanced epithelial-mesenchymal transition activity 5. Additionally, FAM110A shows genome-wide significant association with depressive symptoms in older adults 6, and chr20 duplications of 20p13 containing FAM110A contribute to neurocognitive delays 7.