Chromosome condensation requires the KIF4A–condensin I interaction, but not Aurora-dependent phosphorylation or PRC1 binding. (A) Chromosome spreads of HeLa cells transfected with control or siKIF4A. (B) Box and whiskers plots of the chromosome length measured in FIJI (siControl n = 368, siKIF4A n = 425). The mean is indicated, and whiskers show minimum and maximum values. An unpaired t test with Welch’s correction and 99% confidence intervals was performed (***, P < 0.001). (C) Box and whiskers plots for chromosome length measured in FIJI from spreads of HeLa cells treated with siKIF4A and transfected with KIF4A WT and the indicted mutants (WT KIF4A n = 515, FF1220AA n = 492, T799A/801A = 653, and FF1154AA n = 660). A nonparametric Kruskal-Wallis test to KIF4A was performed (P < 0.0001), and conditions were compared post analysis by Dunn's test (***, P < 0.001). (D) Representative images of chromosome spreads analyzed in C are shown.