Required for normal cytokinesis during mitosis. Plays a role in the regulation of cell proliferation. May be a component of the chromosomal passenger complex (CPC), a complex that acts as a key regulator of mitosis. The CPC complex has essential functions at the centromere in ensuring correct chromosome alignment and segregation and is required for chromatin-induced microtubule stabilization and spindle assembly. Increases AURKB activity. Inhibits apoptosis induced by TGFB1 (By similarity). Overexpression induces swelling of mitochondria and reduces mitochondrial membrane potential (By similarity). Interacts with AURKA, AURKB, BIRC5 and INCENP. May be a component of the CPC at least composed of BIRC5/survivin, CDCA8/borealin, INCENP and AURKB/Aurora-B. Detected at the centrosome and along spindle fibers during prophase and metaphase. Detected at the midbody during telophase. Ubiquitous. Expressed in all normal human tissues studied but overexpressed or underexpressed in many of their malignant counterparts. Protein levels increase during the S phase of the cell cycle, are highest during G2 and mitosis, and decrease to low levels at G1. Levels are lowest at the transition from G1 to S phase. Belongs to the JTB family.