FIG. 6.

T-cell mitogens cooperate with Tat, but not Tax, to enhance the HIV-1 LTR activity in the TAR- or κB element-dependent manner. (A) Tax has no cooperative effect with either PMA or PHA. The LTR-SEAP was cotransfected with or without Tax into Jurkat TAg cells. Twenty-four hours after transfection, the transfected cells were left unstimulated or stimulated with either PMA (50 ng/ml) or PHA (2 μg/ml) for another 24 h. The SEAP activity was quantified as described above. (B) PMA or PHA synergistically activates the HIV-1 LTR in the presence of Tat. The experiment was performed as described above except that the Tat plasmid (0.1 μg) was used to replace Tax. The data are representative of two independent experiments.