Reporter assays with different fibin promoter lengths. (A, D) Various lengths of human genomic sequences upstream of the fibin translation start were amplified and cloned into a pGL3 vector. Murine (B) L929 cells and (C) RAW264.7 cells as well as human (E) HEK293 cells and (F) T98G cells were transfected with the various promoter constructs. RAW264.7 cells and T98G cells served as the respective mouse and human negative controls because no endogenous fibin-mRNA expression was found (see Figure 2C). Luciferase activity was measured 48 h later and normalized to luciferase activity driven by an SV40 promoter with average values of 2,483 cps (L929 cells), 21,975 cps (HEK293), 12,896,311 cps (RAW264.7 cells), and 147,769 cps (T98G cells). Data are given as mean ± SEM of four to seven independent experiments.