MDM2 and neoplasm: To understand the mechanisms by which specific downregulation of mutp53 in cancer cells expressing both wtp53 and mutp53 led to reduced tumor progression, PI staining and flow cytometry were performed using U2OSwt+R175H (Figure 5A) and HCT116wt/R248W (Figure 5B) cell lines, in the absence or presence of Nutlin-3a, an inhibitor of the MDM2-p53 interaction.