FIG. 7.

STAT5 transactivates the minimal CIS gene promoter in a reconstituted COS-7 model. COS-7 cells were cotransfected with the CIS gene promoter (−404CIS-LUC) or with the βCAS gene promoter-luciferase reporter constructs (βCAS-LUC) (lanes 1 and 2) together with vectors encoding the prolactin receptor and STAT5A, STAT5B, or two dominant-negative forms of STAT5 which lack the C-terminal transactivation region (STAT5-Δ749 and STAT5-Δ754) (23), as indicated in the figure (lanes 1 to 6). To normalize the transfections, a β-galactosidase gene was cotransfected in all cases. Luciferase activities were measured after cell stimulation with (COS-PRL-R Prolactin) or without (COS-PRL-R) prolactin. Values were normalized to the β-galactosidase activities and were the means of three independent transfection assays.