Plus end-directed microtubule-dependent motor. May regulate microtubule dynamics during axonal growth (By similarity). Required for normal progression through mitosis. Required for normal congress of chromosomes at the metaphase plate. Required for normal spindle dynamics during mitosis. Promotes spindle turnover. Implicated in formation of bipolar mitotic spindles Has microtubule depolymerization activity. {ECO:0000250; ECO:0000269|PubMed:19351716}.