Jumping translocation breakpoint, also known as JTB, is a member of the JTB family. Jumping translocation (JT) is an unbalanced translocation that comprises amplified chromosomal segments jumping to various telomeres. JTB is expressed in all normal human tissues studied but overexpressed or underexpressed in many of their malignant counterparts. It is required for normal cytokinesis during mitosis. JTB plays a role in the regulation of cell proliferation. It 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.