Fig. 6.

Functional role of the Smad3 isoform protein in activin-regulated promoter activity. HEK293FT cells were transfected with the Smad3 isoform expression plasmid plus the full-length Smad3 expression plasmid and one of two activin-responsive reporter constructs: 3TP-Luc, or CAGA-Luc, and LβT2 cells with FSHβ-Luc; empty vector (pcDNA3.0) was used to adjust total plasmid concentration for each transfection condition. Cells were treated with activin A (30 ng/ml) for 6 hours and then harvested for luciferase assay. For each reporter, promoter activity decreased with increased Smad3 isoform expression. Luciferase activity is expressed as fold induction relative to cells transfected with control vector alone. The data represent the means ± S.E. of three independent experiments performed in quadruplicate.