Haspin inhibitors compromise chromosome alignment. (A) U2OS cells expressing Histone-H2B-mRFP and γ-tubulin–GFP were exposed to vehicle alone (DMSO), and mitotic progression was followed by live confocal fluorescence microscopy. Maximum intensity projections of H2B-mRFP fluorescence from selected frames are shown. Video 1 shows complete data including γ-tubulin–GFP fluorescence. (B and C) As above, for a cell treated with 10 µM LDN-211898 (B) or 10 µM 5-iodotubercidin (C). Arrowheads indicate misaligned or lagging chromosomes. Asterisks indicate the first frame in which cytokinetic furrowing was observed. Also see Videos 2 and 3. Bars, 10 µm. (D) Mitotic defects enumerated from live imaging movies. See Fig. S4 C for further details.