A replicated chromosome includes two kinetochores that control chromosome segregation during mitosis. The centromere proteins CENP-A, CENP-B, CENP-C, CENP-E, CENP-F (also designated mitosin), CENP-H and INCENP are kinetochore proteins that are involved in mitotic events. The centromere proteins are expressed at different levels throughout the cell cycle and are involved in the formation of the centromere and the organization and function of the kinetochore. INCENP, which also is designated inner centromere protein, is a chromosomal passenger protein that is crucial for chromosome segregation. During mitosis it is also required for cytokinesis onset. This protein, which can form a homodimer or a heterodimer, binds directly to microtubules and interacts with AURKB, AURKC, CBX3 and ? Tubulin. This nuclear protein localizes to the mitotic spindle, methaphase chromosomes and during anaphase, to the equatorial cortex.