Figure 4: Aurora B is required for H3T80 phosphorylation. (a) HeLa cells were subjected to no treatment, colcemid arrest, and colcemid arrest in conjunction with ZM447439 treatment. Half of the cells were used to isolate histones and to perform an H3K79me3T80ph western blot, and half of the cells were used to make whole-cell lysate and perform a Cyclin B1 western to control for synchronization. (b) In vitro kinase assay using recombinant Aurora B/INCENP in the presence of 32P-gamma-ATP and biotinylated H3 (1–21); H3 (71–88); H3 (71–88), K79me3 peptides. Bars represent fold mean 32P scintillation counts over cold phosphorylated peptide (±S.E.M.), .