TGF-β1 dose-dependently induces SEAP reporter activity in MFB-F11 cells. A, B: MFB-F11 cells were cultured at different cell densities with the indicated concentrations of TGF-β1 and SEAP activity was measured in the supernatant. (B) shows a higher magnification of the x-axis shown in (A) in the lower range of TGF-β1. C: 3 × 104 MFB-F11 cells/well were incubated with the indicated concentrations of TGF-β1 in B27 supplemented, serum-free DMEM. Note the logarithmic scale. Bars represent mean ± SEM of triplicate wells from one representative experiment. D: 4 × 104 TMLC cells/well were incubated with the indicated concentrations of TGF-β1 in serum-free DMEM. All assays were performed in 100 μl total volume in 96-well tissue culture plates and SEAP or luciferase activity was measured after 24 h induction in 10 μl supernatant or 50 μl cell pellet respectively. * P < 0.05; ** P < 0.001, Student's t test compared to 0 pg/ml TGF-β1 in C.