Metaphase cells deficient in KIF18A and KIF15 display chromosome alignment and spindle length abnormalities. (A and B) Metaphase cells arrested in MG132 with antibody staining for endogenous KIF18A (A) or endogenous KIF15 (B). (C) Quantification of FWHM (left) and spindle length (right) for individual cells treated with the indicated siRNAs. n.s., not significant; ****, adjusted P < 0.0001 with 95% confidence interval by one-way ANOVA with Tukey’s multiple comparisons test. (D) Quantification of KIF18A (left) and KIF15 (right) knockdown efficiencies for cells analyzed in (C). For the double knockdown quantification, one coverslip each was stained for each kinesin. ****, adjusted P < 0.0001 with 95% confidence interval by one-way ANOVA with Tukey’s multiple comparisons test as compared with control siRNA treatment. Error bars represent SD. Data in C and D were obtained from two independent experiments with the following cell numbers: control siRNA (103), KIF18A siRNA (113), KIF15 siRNA (82), and KIF18A and KIF15 siRNA (184).