Accumulation of SAC proteins in the kinetochores of Plk1-deficient megakaryocytes. (A) Immunodetection of Bub1 (green) and centromeres (ACAs, magenta) in Plk1(Δ/Δ) cells or control cells treated with Taxol or the Plk1 inhibitor BI2536. Cdc20-deficient cells were used as a control of SAC-independent mitotic arrest. DAPI (blue) was used to stain DNA. (B) Immunodetection of Mad2 (red) and centromeres (ACAs, magenta) in Plk1(Δ/Δ) cells or control cells treated with Taxol or the Plk1 inhibitor BI2536. Cdc20-deficient cells were used as a control of SAC-independent mitotic arrest. DAPI (blue) was used to stain DNA. Scale bars, 10 μm (insets, 2 μm).