Figure 3. Effect of exogenous Shh on in vitro corneal epithelial cell migration. Mean number (±S.E.M) of wild-type corneal epithelial cells per ten fields of view migrating in 60 min across Boyden chamber membrane toward a source of serum-free corneal culture medium (sfCCM; ‘control’), CCM with 10% fetal calf serum (FCS), sfCCM with 50 ng/ml mouse epidermal growth factor (EGF) or sfCCM with 5 μg/ml rhShh-N (Shh). *** represents p<0.001.