BRISC is important for normal mitosis in mammalian cells. (A–C) Mitotic defects in ABRO1 siRNA-transfected HeLa cells. Cells transfected with control or ABRO1 siRNA were fixed in cold methanol and immunostained for α-tubulin (green) and ABRO1 (red); DNA was stained with DAPI. ABRO1 was efficiently silenced. Spindle structures were categorized based on the stage of mitosis. Bars, 5 µm. (A) Representative images of multipolar defects in ABRO1-depleted metaphase cells. (B) Representative examples of lagging chromosomes and aberrant cytokinesis in ABRO1-depleted anaphase and telophase cells, respectively. (C) Representative images of multinuclei defects in ABRO1-depleted postmitotic interphase cells. (D–F) Quantitative analysis of the mitotic spindle structures that are shown in A–C. Error bars show mean ± SD of three independent experiments. **, P < 0.01; ***, P < 0.001; Student’s t test. (G) Representative images of the rescue efficiency in CFP-ABRO1res–transfected metaphase cells. ABRO1 siRNA-transfected HeLa cells were cotransfected with plasmid CFP-ABRO1 WT, which is sensitive to ABRO1 siRNA, or CFP-ABRO1res, which is resistant to ABRO1 siRNA. The mitotic defects shown in A–C were observed. Bars, 5 µm. (H) Quantification of the mitotic spindle structures shown in G. Data from three independent experiments. ***, P < 0.001; Student’s t test. (I) Protein samples from cells treated as shown in H were analyzed by Western blotting. Actin was used as a loading control. Error bars show mean ± SD.