Figure 6. Effect of inhibition of transforming growth factor (TGF)-β receptor I or Smad3 phosphorylation on TGF-β2-driven extracellular matrix (ECM) stimulation. Optic nerve head (ONH) astrocytes and lamina cribrosa (LC) cells were pre-incubated with a type I TGF-β receptor inhibitor (SB431542, 10 uM) or an inhibitor of Smad3 phosphorylation (SIS3, 25 and 50 uM), 1 h before treatment with recombinant TGF-β2 (5 ng/ml) for 24 h. A: Total cell lysates, and B: the conditioned medium were subjected to western blot analysis of fibronectin. A: The effect of SB431542 on TGF-β2 stimulated cellular fibronectin (FN) was assessed by western blot in ONH astrocytes and LC cells. B: Effect of inhibition of phosphorylation of Smad3 on TGF-β2 stimulated ECM was examined by western blot analysis of secreted FN in ONH astrocytes and LC cells. Inhibition of Smad3 phosphorylation reduced TGF-β2 stimulated FN secretion in ONH astrocytes and LC cells.