Tax-P79AQ81A properly activates a NF-κB promoter in either cell lines or primary CD4+T cells. NF-κB promoter activity in Tax-transfected HeLa cells (A), 293 T cells (B), CEM T cells (C), and primary CD4+ T cells (D). Cells were transfected with a control plasmid or with the Tax-His constructs along with the NF-κB reporter plasmid and the Renilla luciferase expression plasmid for normalization. To validate the experiments, the M22 (defective for the NF-κB pathway) and M47 (defective for the CREB pathway) mutants were included in each experiment. Fold induction was calculated by dividing the firefly/renilla ratio of each Tax protein with the firefly/renilla ratio obtained with the control plasmid. The results represent the means and standard error of the means (SEM) from at least four independent experiments performed in duplicates. ns: not statistically significant.