Activation of gene expression via the NF-κB pathway correlates with Tax-1 and Tax-2B ubiquitination and sumoylation status. 293T cells were cotransfected with 50 ng of vectors expressing wild type or mutant Tax-1 or Tax-2B and 250 ng of NF-κB-Luc reporter plasmid. Fifty ng of the phRG-TK Renilla Luciferase vector were added to the reaction to normalize for transfection efficiency. Cells were lysed and the luciferase activity was measured. Mutant Tax-1 and Tax-2B activities were expressed as percentages of WT Tax activities. The values reported are the averages of three independent experiments. Comparable levels of wild type and mutant Tax proteins in the lysates were ascertained by Western blot analysis using Tax-1 and Tax-2B antibodies.