(A) Activation of the hiNOS promoter by HTLV-Itax gene. The described hiNOS promoter constructs (1 μg) were transiently cotransfected with 5 μg of pH2R40M (+Tax) or with 5 μg of pH2Rneo (−Tax) into Jurkat cells. Luciferase activity normalized by protein content was expressed as the mean ± SEM of at least three experiments. The relative luciferase activity was calculated from the luciferase activity of each reporter plasmid relative to the value of pGLNOS-0.11, cotransfected with pH2Rneo and assigned a value of 1.0. The induction ratio represented the average stimulated value divided by average unstimulated value. (B) Effect of point mutation on the inducibility of luciferase activity. pGLNOSa or pGLNOSa bearing a 3-bp mutation in the NF-κB site (pGLNOSκBm) were cotransfected into Jurkat cells with 5 μg of pH2R40M (+Tax) or 5 μg of pH2Rneo (−Tax). The NF-κB site (−115 to −106; GGGACACTCC) in the hiNOS promoter was mutated to CTCACACTCC. Tax-dependent increase in reporter gene activity was expressed as a percentage of the value of pGLNOSa cotransfected with pH2R40M. Data represent the mean ± SEM of three experiments.