FIG. 1.

(A) Schematic diagram of HTLV-1 Tax indicating the relative positions of point mutations and functional domains. The ΔN81 and ΔN109 truncations are shown fused to the NLS of the SV40 large T antigen. (B) Cytotoxicity induced by the wild-type Tax (WT) and Tax mutants was quantified by transient cell death assays in HeLa cells as described in Materials and Methods. Transactivation phenotypes for each Tax vector were confirmed by cotransfection of HeLa cells with the HTLV-LTR-Luc (1 μg) (C) or NF-κB-Luc (1 μg) (D) reporter construct with various Tax expression plasmids (2 μg). CMV-Renilla (0.1 μg) was added to control for transfection efficiencies. (E) The empty N2 vector or a wild-type Tax expression construct was cotransfected together with increasing amounts (0.05, 0.1, and 0.15 μg) of the IκBα S32/34A plasmid in transient cytotoxicity assays. Total amounts of transfected DNAs were held constant by adding the RcCMV vector; CMV-Renilla (0.1 μg) was added to control for transfection efficiencies. Effects of IκBα S32/34A expression on Tax-mediated transactivation was assayed by cotransfecting HeLa cells with the NF-κB-Luc (1 μg) (F) or HTLV-LTR-Luc (1 μg) (G) reporter plasmid with a wild-type Tax expression construct (2 μg). Error bars represent standard deviations between experiments.