LBH589 induces phosphorylation of histone H2A.X. Cells were treated with the indicated concentrations of LBH589 for 24 hours. Subsequently, Western blot analysis of phosphorylated histone H2A.X was performed on the cell lysates from MOLT-4 and Reh cells. The levels of β-actin served as loading controls. Results are representative of 3 independent experiments.