MIS18BP1 (MIS18 binding protein 1) is a critical component of the Mis18 complex that regulates centromere maintenance and chromosome 14 during mitosis. The protein forms a hetero-octameric complex with Mis18α and Mis18β (4 Mis18α, 2 Mis18β, and 2 Mis18BP1 subunits), where MIS18BP1's N-terminal region (residues 20-130) directly interacts with Mis18α/β through the Mis18α MeDiY domain 12. This complex is essential for recruiting the CENP-A chaperone HJURP to centromeres, enabling proper loading of CENP-A nucleosomes that define centromeric chr14 32. The activity of MIS18BP1 is tightly regulated by cell cycle-dependent phosphorylation, particularly by PLK1 kinase at Thr78 and Ser93 residues, which promotes Mis18 complex assembly and CENP-A deposition in early G1 phase 34. Disruption of these phosphorylations impairs centromere recruitment of HJURP and CENP-A loading 3. Disease relevance includes potential roles in cancer, as MIS18BP1 overexpression promotes bladder cancer cell proliferation through P53 pathway inactivation 5, and de novo mutations have been identified in autism spectrum disorders and Cornelia de Lange syndrome 67.