Tax abrogates activation of Dkk1 expression by HBZ. (A) Levels of Dkk1 in culture media from cells transfected with the indicated vectors. Dkk1 levels from culture media were detected by ELISA and normalized to the level of Dkk1 from the medium of cells transfected with the empty vector. The graph shows data from three independent transfection assays, with Dkk1 protein levels shown relative to values obtained from cells containing the pSG5 empty vector. A 1:1 stoichiometric ratio was used for cotransfection of HBZ and Tax expression vectors. (B) Levels of Dkk1 mRNA from cells transfected with the indicated vectors. Levels of Dkk1 mRNA were normalized to UBE2D2 mRNA following quantitative real-time PCR of reverse transcribed total cellular RNA. The graph shows data from two independent experiments, with Dkk1 mRNA levels shown relative to values obtained from cells containing the pSG5 empty vector (set to 1). (C) Expression of HBZ and Tax after transfection. Total cellular lysates (25 μg) were subjected to Western blot analysis using antibodies directed against Tax, Myc (C-terminal epitope tag on HBZ) and β actin, as indicated.