Kinesin-related antiparallel sliding motor protein; involved in mitotic spindle positioning; sliding activity promotes bipolar spindle assembly and maintenance of genome stability; inhibits spindle elongation, destabilizing late anaphase spindle microtubules (MTs) that polymerize beyond the midzone; required for plus-end directed kinetochore movement along metaphase MTs enabling chromosome biorientation and congression; involved in chromosome movement towards the spindle pole during anaphase A