BUB1B and cancer: In addition, mitotic checkpoint serine/threonine-protein kinase BUB1 beta is an enzyme that is encoded by the BUB1B gene.[58] This gene encodes a kinase involved in spindle checkpoint function and chromosome segregation.[59] Incidentally, impaired spindle checkpoint function has been found in a variety of cancer, which may have a potential relationship with BUBIB.[47]