An inhibitor of the kinesin-related motor protein Eg5 with potential antineoplastic activity. Litronesib selectively inhibits the activity of Eg5, which may result in mitotic disruption, apoptosis and consequently cell death in tumor cells that are actively dividing. The ATP-dependent Eg5 kinesin-related motor protein (also known as KIF11 or kinesin spindle protein-5) is a plus-end directed kinesin motor protein that plays an essential role during mitosis, particularly in the regulation of spindle dynamics, including assembly and maintenance.