(F) GFP and MIG-6 knockdown BT549 cells transfected with the indicated plasmids were treated with MG132, subjected to immunoprecipitation (IP) with Flag-tag or HIF1α antibody, followed by immunoblotting analysis. MG132 was used to rescue HIF1α protein degradation mediated by MIG-6 knockdown, leading to similar HIF1α protein levels in control and MIG-6 knockdown BT549 cells, which were used as the input to examine the role of MIG-6 in the interaction between HIF1α and HAUSP. 