Fig. 3. TGF-ß1 treatment increases the half-life of decay of I{kappa}B-{alpha} in Hs578T breast cancer cells. In A, cultures of Hs578T cells were plated at a density of 2 x 105 cells/P100 dish the day before treatment. Cells were treated with 5 ng/ml TGF-ß1 or carrier solution for 48 h and then incubated in the presence of the protein synthesis inhibitor 20 µg/ml emetine for 0, 1, 2, or 4 h. Cytoplasmic extracts were prepared, and equal amounts (30 µg) were subjected to immunoblot analysis for I{kappa}B-{alpha} or I{kappa}B-ß. In B, the autoradiograph for a representative experiment for I{kappa}B-{alpha} was quantified by densitometric analysis, and the data were presented as a function of the amount present at time zero, set at 100% for the control and TGF-ß1-treated samples. {circ}, BSA control; •, treated with TGF-ß1.