Chromokinesin overexpression increases polar ejection force experienced by short chromosomes. (A) eYFP-Cdc20 PtK2 cells overexpressing Kid (Kid OE) were treated with STLC and monopolar spindles were followed and analyzed. Kid-HaloTag was visualized using JF549 dye. See also Video 4. (B) The average distance of kinetochores from poles was used to assess the magnitude of pushing force on long and short chromosomes in Kid OE cells compared with control cells (mean ± SD; unpaired t test).