Effect of NF-κB subunit on NF-κB transcriptional activity. Jurkat cells were transfected by electroporation with a reporter plasmid (5 μg) containing the luciferase gene fused to five repeats of the κB motif of the IL-2R gene and enhancerless promoter of HTLV-I (κB-LUC) along with combinations of the cDNA expression plasmids encoding p50 (5 μg), p65 (5 μg), and c-Rel (5 μg) indicated at the bottom of the panel. After 24 hours of growth, cells were harvested and assayed for luciferase activity. Increase of the luciferase activity in cell extracts is shown relative to that after parental plasmid transfection. The mean ± standard error of mean (SEM) for three independent assays is presented.