BuGZ contributes to MT assembly and reduces S196 phosphorylated xMCAK. (A) MT asters and spindles assemble around AurA beads at the indicated time points in mock-depleted XEEs or XEEs depleted (dep) of xBuGZ or xTPX2 or treated with MLN8237. Bar, 10 µm. (B and C) MT aster lengths (B) and percentages of bipolar spindles (C) were quantified. Approximately 50 (B) and ∼200 (C) AurA bead structures were quantified in three independent experiments. (D) XEE mock-depleted by unimmunized rabbit IgG, xBuGZ, or xTPX2 antibodies or treated with MLN8237 were analyzed by Western blotting probing with the indicated antibodies. The means and SEM are graphed. Student’s t test: *, P < 0.05; **, P < 0.01; ***, P < 0.001.