Treatment with p150-CC1 or 70.1 displaces Kif2a, but not MCAK from spindle poles. Assembled spindles, after addition of buffer, p150-CC1, or 70.1, were processed for immunofluorescence. MCAK staining in control (A and D), p150-CC1–treated (2 μM, 15 min; B and E), and 70.1-treated (1 mg/ml, 15 min; C and F) spindles. (A–C) Overlays (tubulin, red; DNA, blue; MCAK, green). (D–F) MCAK alone. (G–I) Line scans of fluorescence intensity (MCAK, green; tubulin, red; arbitrary units) across the pole to pole axis of the spindles shown in A–C. Kif2a staining in untreated (J and M), p150-CC1–treated (2 μM, 15 min; K and N), and 70.1-treated (1 mg/ml, 15 min; L and O) spindles. (J–L) Overlays (tubulin, red; DNA, blue; Kif2a, green). (M–O) Kif2a alone. (P–R) Line scans of fluorescence intensity (Kif2a, green; tubulin, red; arbitrary units) across the pole to pole axis of the spindles shown in (J–L). (S and T) Spindles were treated for 15 min with p150-CC1 (4 μM) or control buffer and the relative amount of Kif2a (S), or MCAK (T), and tubulin associated with partially purified spindle pellets was analyzed by immunoblotting. (U) Quantitation of spindle-associated Kif2a and MCAK relative to tubulin from measurements of immunoblot band intensities (mean ± SD, two independent experiments), normalized to intensities from untreated spindles. Bars, 10 μm.