TP53 and cancer: In order to understand the p53-independent roles of the Mdm2-MdmX complex in cancer cells, we used three approaches: the knockdown of each component of the complex, using two different siRNAs for Mdm2 and two different siRNAs against MdmX, as well as the siRNA scramble used as a control, and a pharmacological strategy involving treatment with the inhibitor of the Mdm2/MdmX E3-ligase activity, MEL23, or DMSO as a vehicle control.