Nutlin-3a activates p53 signaling in LNCaP cells. A) Antitumor activity of Nutlin-3a. Cells were incubated with nutlin-3a for 5 days and cell growth/viability measured by the MTT assay. B) Changes in key proteins. Exponentially proliferating LnCAP cells were treated with 10 μM Nutlin-3a, or DMSO for 20 h and cell lysates were analyzed by Western blotting. C) Nutlin inhibits cell cycle progression. LNCaP cells were treated with 10 μM nutlin-3a for 20 h and analyzed by BrdU labeling and flow cytometry. Box indicates the S phase compartments. D) Nutlin induces dose and time-dependent apoptosis in LNCaP cells. Cells were incubated with nutlin-3a at the indicated concentrations and the percentage of the Annexin V-positive cells was determined. Time-dependant apoptosis was determined at 10 μM concentration.