A. MG63, U2OS, A673 and HT1080 cells were treated 500nM MK1775 for 24 hours and stained for phosphorylated Histone 3 (AlexaFluor 647, red) and cleaved caspase 3 (AlexaFluor 488, green) and counterstained nuclei with DAPI and visualized using a Zeiss Upright Fluorescence microscope. B. MG63, U2OS, A673 and HT1080 cells were treated with 500nM MK1775 for 24 hours and the percentage of total phosphorylated Histone 3 positive cells in control versus MK1775 treated was determined by FACS, fold change phospho H3 positive cells in control versus 500nM MK1775.