(A) Representative immunoblots from U2OS, A549, HT1080 and SAOS cell lysates collected 24h after Nutlin treatment (8μM) probed using antibodies specific against p53, p21 and MDM2. Actin expression was detected as a loading control. (B) Representative DNA content profiles of untreated and Nutlin treated (8μM) U2OS, A549, HT1080 and SAOS cells. Cells were fixed, stained with propidium iodide and analyzed by flow cytometry for DNA content. DNA profiles are representative of three independent experiments.