Centrosomal Aki1 is essential for formation of bipolar spindles. (A) HeLa cells were transfected with control, Aki1-2, or Aki1-3 siRNA. Cell lysates were immunoblotted with the indicated antibodies. (B–D) HeLa cells were transfected with control or Aki1-2 siRNA and costained for Aki1 (green) and γ-tubulin (γ-tub; red), or for α-tubulin (α-tub; green) and γ-tubulin or pericentrin (red; C and D). (E) Percentage of multipolar cells of mitotic cells in control, Aki1-2, or Aki1-3 siRNA–treated cells. (F) Percentage of multipolar cells in control or Aki1-2 siRNA–treated cells in interphase or mitosis. (G) HeLa cells stably expressing AcGFP-WT or ΔC815-Aki1 (green) were counterstained for γ-tubulin (red). (H) Percentage of multipolar cells of mitotic cells in control or Aki1-2 siRNA–treated cells expressing AcGFP-mock, AcGFP-WT-rAki1, or AcGFP-ΔC815-rAki1. Error bars represent SD of triplicate experiments (150–200 total cells were scored per condition). Bars, 5 µm.