Tax sumoylation is involved in the formation of Tax nuclear bodies and transcriptional activation. (A-B) HeLa cells were transfected with either Tax plasmid together with HA-Ub (A) or HA-SUMO3 (B), and stained by dual immunofluorescence with anti-Tax (green) or anti-HA (red) mabs. (C-D) HeLa cells were transfected with a control plasmid or the Tax plasmid and stained with anti-SUMO, anti-Tax (green), anti-PML, or anti-p300 (red) antibodies. (E) HeLa cells were transfected with Tax K6-8R or Tax K6-8R-SUMO1 plasmids and stained with anti-Tax antibodies. (F) Jurkat cells were cotransfected with the NF-κB-Luc reporter, renilla luciferase, and the plasmid encoding wild-type Tax, Tax-SUMO1, Tax K6-8R, or Tax K6-8R-SUMO1. Activity of the wild-type protein was set to 100%.