Expression of Thy-1 (A), α-SMA (B), and fibronectin (C) relative to GAPDH in cat corneal keratocytes cultured for 72 hours with different concentrations of TGF-β1. Significantly greater relative expression of all three proteins was observed in anterior cells at 0.1 ng/mL TGF-β1 compared with posterior cells (Thy-1, P < 0.0001; α-SMA, P = 0.004; fibronectin, P < 0.0001). With 1 ng/mL TGF-β1, this difference begins to resolve, whereas exposure to 2 ng/mL TGF-β1 induces near maximal relative expression of all three proteins in both anterior and posterior cells.