Spry specifically blocks TGFβ-activity in lens epithelial explants. Epithelial explants prepared from postnatal-d-15 WT murine lenses (A–D) or transgenic mouse lenses overexpressing Spry1 (E–H) were exposed to no TGFβ (A, E), 25 pg/mL TGFβ2 (B, F), 50 pg/mL TGFβ2 (C, G) or 200 pg/mL TGFβ2 (D, H) for up to 5 d before immunolabelling for α-sma (green), and counterstaining cell nuclei with propidium iodide (red). Epithelial cells in lens explants prepared from WT mice underwent an EMT (based on α-sma reactivity) with exposure to 25 pg/mL of TGFβ (B), and the degree of this EMT was progressively more pronounced with increasing concentration of TGFβ (C, D). In contrast, lens epithelial cells overexpressing Spry1 were more resistant to the effects of TGFβ, with little to no response with either 25 pg/mL (F) or 50 pg/mL (G) TGFβ. At much higher concentrations of TGFβ (200 pg/mL), lens cells overexpressing Spry1 underwent an EMT with strong reactivity for α-sma (H), comparable to that seen in WT lens cells (D). Scale bar, 20 µm.