FIG. 2.

Functional interplay between C/EBPβ and Smad3/4 in the presence of HIV-1 Tat. U-87MG cells were transfected with 5.0 μg of TGF-β1-CAT reporter plasmid (full length) alone or cotransfected with 5.0 μg of C/EBPβ (A–B), Smad3 (A and C), Smad4 (B and C), or Tat (C) expression plasmids using various combinations. The amount of DNA used for transfection was normalized with pcDNA₃ plasmid. Cell extracts were prepared 48 h after transfection, and CAT assays were performed. The values shown on the top of each bar represent the fold activation over the basal promoter activity arbitrarily set at one. The data represent the mean value of at least three separate transfection experiments (SE ± 15%).