Spry-deficient lenses display increased immunolabeling for ERK1/2 (pERK1/2) phosphorylation in the postnatal mouse lens. Representative anterior (A, A’, B, B’) and equatorial (C, C’, D, D’) sections of postnatal-d-21 WT (A, A’, C, C’) and Spry-deficient (B, B’, D, D’) lenses using MLR10-Cre, immunolabeled for pERK1/2 (A’-D’) or counterstained with Hoechst dye (A–D). Compared to the WT lens, Spry-deficient lenses displayed stronger labeling for pERK1/2 in the epithelial (le) and secondary fiber cells (lf), especially at the lens equator (D’, arrow), with increased labeling also throughout the more anterior central lens epithelium, with very strong labeling in isolated cells (B’, arrow). (E) Western blotting of cell lysates from postnatal-d-15 WT (left panels) or Spry-deficient (Spryfl/fl/2fl/fl, right panels) lenses (n = 60), immunolabeled for either pERK1/2 (top panels), total ERK1/2 (tERK1/2, middle panels) or GAPDH (lower panels). Spry-deficient lenses demonstrated stronger labeling for pERK1/2 compared with WT lenses. Scale bar, A, A’, B, B’ = 25 µm; C, C’, D, D’ = 65 µm.