Kif2A-mediated central spindle sizing for cytokinesis. (A) EGFP–α-tubulin cells codepleted of Kif2A and MKLP1. Cells regressed during or after furrow ingression (labeled as early or late regression, respectively). Bar, 5 µm. (B) Frequency of early or late regression in each sample. For each treatment, ≥50 cells from two independent experiments were analyzed. (C) Model for central spindle sizing by Kif2A and Aurora B. The Aurora B activity gradient is formed around stem bodies. In the region where Aurora B concentration is high, Kif2A is inactivated through phosphorylation on T97, whereas it actively depolymerizes MT ends outside the region. This mechanism prevents overshortening of icMTs and guarantees proper sizing of icMTs.