Activity of HTLV Rex1 and Rex2 on MMTV RmRE-containing reporter plasmids in human cells. A. Reporter activity in Jurkat T cells. B. Reporter activity in 293T cells. Values are reported as in Figure 2, except that Rex1GFP or Rex2GFP expression plasmids were used. C. Western blotting confirms similar expression of Rem and Rex. Samples from Jurkat transfections are shown and analyzed with antibodies specific for GFP (upper panel) or actin (lower panel). Size markers are given in kilodaltons.