Kif15 drives spindle assembly in all three KIRCs. (A) Spindles assemble through a monopolar intermediate in KIRC-2 and -3 cells. Sequential images of a KIRC-2 and -3 cell entering mitosis taken by time-lapse DIC microscopy. Time is indicated in minutes relative to the initial frames. Intermediate frames reveal chromatin rosettes and final frames show metaphase plates. Bar, 10 µm. (B) Kif15 depletion induces a mitotic arrest in all three KIRCs. Bright-field images of indicated cell types 1 d after transfection with nontargeting (Control) or Kif15-targeting (-Kif15) siRNAs. Bar, 200 µm. (C) Quantitation of B. Values represent the mean MI of indicated cell types 1 d after transfection with nontargeting (gray) or Kif15-targeting (green) siRNAs. Error bars, ± SEM; n ≥ 800 cells from three independent experiments. (D) Kif15 depletion prevents spindle assembly in all 3 KIRCs. Values represent the mean MPI of indicated cell types 1 d after transfection with nontargeting (gray) or Kif15-targeting (green) siRNAs. Error bars, ± SEM; n = 300 cells from three independent experiments. *, P ≤ 0.02 relative to control. (E) Kif15 depletion leads to massive cell death in all three KIRCs. Values represent the normalized luminescence of indicated cell types 2 d after transfection averaged over three experiments. Error bars, ± SEM; *, P ≤ 0.01 relative to the parental HeLa line.