Figure 3: miR-155 promoter activity was increased by Tax through both NF-κB and AP-1 activation. (a) Putative transcription factor binding sites in the miR-155 promoter are presented in the left panel. Luciferase reporter plasmids with either wild-type or mutant miR-155 gene promoter together with either Tax expression plasmid (Tax (+)) or empty vector (Tax (−)) were transfected into Jurkat cells. Then the cells were incubated for 48 h. Luciferase reporter activity is shown as a fold induction relative to the levels measured in the cells transfected with the empty vector (Tax (−)). (b) Jurkat cells were transfected with following plasmids: luciferase reporter plasmids of wild-type miR-155 promoter together with either Tax wild type (WT), M22, 703 expression plasmids, or empty vector. Luciferase activity was analyzed 48 h later. Values are the mean ± SD from three separate experiments.