Panobinostat synergizes with MK-1775 in BxPC-3 cells. A, BxPC-3 cells were treated with panobinostat and MK-1775, alone or combined, for 48 h and subjected to PI staining and flow cytometry analysis. B, CI vs. Fa plot (combination index vs. fraction affected) for the apoptosis data presented in Panel A. The CI values were calculated using CompuSyn software. C, BxPC-3 cells were treated with panobinostat and/or MK-1775 for 48 h and subjected to PI staining and flow cytometry analysis. D, protein extracts were subjected to Western blotting and probed with anti-PARP, -p-H3, -p-CHK1, -CHK1, -p-CDC25C, -p-CDK1, -CDK1, -p-CDK2, -CDK2, -γH2AX, or -β-actin antibody. E, BxPC-3 cells were treated with panobinostat and MK-1775 for 48 h, then stained with annexin V/PI and subjected to flow cytometry analysis. The data are presented as means ± standard errors from one representative experiment. F, CI vs. Fa plot (combination index vs. fraction affected) for the apoptosis data presented in Panel E. The CI values were calculated using CompuSyn software.