The metastasis-associated 1 (MTA1)-induced degradation of DNA protein kinase (DNA-PK) was mediated by mouse double minute 2 (MDM2). (A) Western blotting was performed in HuH6 cells cotransfected with DNA-PK-HA, pEGFP-MTA1, pEGFP-N1 plasmids, and increasing amounts of MDM2-His plasmid (0.5 and 1 μg). (B) Western blotting was performed in HuH6 cells cotransfected with pEGFP-MTA1, pEGFP-N1 plasmids, and increasing amounts of MDM2-His plasmid (0.5 and 1 μg). (C) Western blotting was performed in HuH6 cells cotransfected with pEGFP-MTA1, pEGFP-N1, MDM2-His, and MDM2-mutated plasmids. (D) Whole cell extracts from HuH6 cells transfected with pEGFP-N1, pEGFP-MTA1, MDM2-His, and MDM2-mutated plasmids were analyzed using Western blotting. (E) Whole cell extracts from HuH6 cells that were transfected with pEGFP-N1 or pEGFP-MTA1 were analyzed using Western blotting. Shown are representative blots and quantification of three independent experiments, *P < 0.05; **P < 0.01, t-test. (F) Whole cell extracts from HuH6 cells that were transfected with control small-interfering RNA (siRNA) or MDM2 siRNA were analyzed using Western blotting. Shown are representative blots and quantification of three independent experiments, *P < 0.05, t-test. (G) Whole cell extracts from pEGFP-N1 or pEGFP-MTA1-transfected HuH6 cells that were treated with control siRNA or MDM2 siRNA were analyzed using Western blotting. Shown are representative blots and quantification of three independent experiments, **P < 0.01, t-test.