Fig. 4. Expression of occludin and claudin-1 proteins in growth factor-stimulated thyrocytes. Cultures were exposed to TGF-ß1 (10 ng/ml) and/or EGF (10 ng/ml) for the indicated times, after which cell lysates at equivalent protein concentrations were analysed with SDS-PAGE and western blotting. ß-actin was used as an internal control for equal protein loading. E, EGF; T, TGF-ß1.