LMP-1 inhibits BAX promoter activity and protein expression. (A) CAT assay of HEK 293-T cells cotransfected with pBAX-CAT (lanes 1-4) or pHIV-1-LTR-CAT (lanes 5-8) in combination with pHEBo (lanes 1,5), pLMP-1 (lanes 2,6), pcDNA-3 (lanes 3,7), or pK15 (lanes 4,8), or transfected with pHEBo only (lane 9). (B) Different cell lines were cotransfected with pBAX-CAT (top row) or pSV2-CAT (bottom row) and pLMP-1 (▪), pK15 (▦), or the control vectors (pHEBo for pLMP-1; pcDNA-3 for pK15; □). CAT activity in transfections with the control vector was set to 100% and compared with CAT activity in the presence of pLMP-1 and pK15. (C) Western blot analysis of LMP-1 (top), Bax (middle), and GAPDH (bottom) protein in 1852.4 cells. Cells were maintained in the absence of tetracycline for 7 days and subsequently 2 μg/mL tetracycline was added for 6 days. DG75 cells that express neither LMP-1 nor Bax were used as a control (right lane). (D) 1852.4 cells were grown 6 days in the absence (-Tet, left) or presence (+et, right) of 2 μg/mL tetracycline and transfected with pBAX-CAT (□) or pSV2-CAT (▪). CAT activity was measured as described for panel B. (B,D) The means and standard deviations of 3 independent experiments are shown.