Impact of gemcitabine and MK-8776 on cell cycle perturbation of MDA-MB-231 cells. A. Cells were incubated with 0 – 50 nmol/L gemcitabine for 24 h without (left) or with (right) 1 μmol/L MK-8776. The drugs were then removed and cells incubated for an additional 24 or 48 h. Cells were then analyzed for DNA content by flow cytometry. B. Similar to A except cells were incubated with gemcitabine for only the first 6 h, while MK-8776 was added only from 18–24 h.