Antisense oligonucleotides to p65, but not p50 or c-Rel, abrogate Tax inhibition of p53. Jurkat lymphocytes were transfected with use of Superfect reagent with 4 × NF-κB–Luc (A) or PG13-Luc (B) and Tax (+; 2 μg) and p53 (+; 0.4 μg) in the presence or absence of the indicated antisense oligonucleotide (AS; 100 nM). Cells were harvested 24 hours after transfection, and activity was measured. Results represent an average of at least 3 independent experiments. Error bars indicate SD. (C) The expression levels of p53, Tax, p50, p65, and c-Rel are shown. (D) A titration of Tax plasmid was performed in Jurkat cells. Cells were transiently transfected with PG13-Luc reporter plasmid in the absence or presence of p53 plasmid. Increasing amounts of Tax plasmid (0.5, 1.0, 2.0 μg) were cotransfected, and the luciferase activity was measured. The arrow indicates the concentration of Tax plasmid used in other Jurkat transfections. (E) Jurkat cells were transiently cotransfected with PG13-Luc reporter construct, p53 (+), and Tax (+) in the absence (–) or presence of increasing amounts of p50, p65, or c-Rel (0.5 μgor1.0 μg). Cells were harvested 24 hours after transfection, and luciferase activity was measured. Activity is indicated as percentage of p53 activity and represents results from at least 3 independent experiments. Error bars indicate SD. (F) Western blot analysis indicates the protein expression levels for Tax (Tab172) and p53 (DO-1).