Fli-1 transactivation of the GPIX promoter in 293T kidney fibroblasts. (A) Left: Diagrams of the luciferase reporter constructs used in Fli-1 transactivation assays. The open boxes identify intact GPIX Ets sites. The crossed out box identifies the region of the GPIX promoter containing the Ets site that is replaced with irrelevant sequence (See Materials and Methods). Plasmid pXP2 is a promoterless construct that encodes the luciferase gene. (A) Right luciferase activity, indicated as light units, generated in transiently transfected 293T kidney fibroblasts. Each sample was transfected with 1.5 μg of luciferase reporter construct and 4.5 μg of the Fli-1 expression vector, CMVFli-1, or nonspecific plasmid, normalized using a CMVβgal control plasmid. Error bars represent deviations between duplicate samples. Each plasmid was tested in at least seven independent experiments. (B) shows an immunoblot analysis of lysates derived from 293T kidney fibroblasts transfected with either pPCR3, the empty expression vector lacking Fli-1, or CMVFli-1. Arrows identify the two isoforms of Fli-1 and numbers indicate the migration pattern of molecular weight markers.