Tumor cells derived from Mdm2/MdmX/p53-triple deficient (TKO) mice were transduced with FL or MdmX deletion constructs (relative MdmX mRNA levels: Mock, 1.0; FL, 6.6±3.6; dRING, 12.1±7.0; dZnF, 23.5±2.8; dZnF-dRING, 7.4±2.3). The gene discussed is MDM4; the disease is neoplasm.