To probe the role of midzone microtubules in cytokinesis, the formation of spindle midzone was blocked by treating Normal Rat Kidney epithelial cells with a topoisomerase II inhibitor, ICRF 187. The treatment inhibits the separation of sister chromosomes and block the creation of midzone space, without affecting microtubule bundle formation in the vicinity of tangled anaphase chromosomes. The organization of midzone microtubules is therefore seriously disrupted by the lack of interzonal space. |