MDM2 and osteosarcoma: As yet another approach to show that TFII-I and Mdm2 might be able to interact not only in cell lysates but also in living cells, we designed a relocalization assay in which GST and a GST-tagged TFII-I mutant lacking the nuclear localization signal (TFII-IΔNLS) were ectopically expressed in human osteosarcoma U2OS cells, either alone or in combination with exogenous Mdm2.