FIG. 3.

Basal and activated promoter activity: fine-tuning of the LTR transcriptional rate. Sup-T1 cells were transfected with a reporter plasmid containing the luciferase gene downstream of the wild-type(WT) LTR or the artificial LTRs with the indicated number of tetO elements. Luciferase activity was measured on day 3 posttransfection, and data represent the averages of three independent experiments. (A) Basal transcription. (B) Transcription activated by rtTA (2Δ tetO, 2 tetO, 8 tetO LTR: pCMV-rtTA) or Tat (WT LTR: pcDNA3Tat).