Variations in MMP-1 and MMP-2 expression upon treatment of dermal fibroblasts with bortezomib or TGF-β or both. mRNA and protein extracts from treated fibroblasts were processed as described in the legend of Figure 1. The increases in mRNA levels for MMP-1 (a) and MMP-2 (b) are reported. The data represent the mean ± standard deviation of two independent experiments; *P < 0.05 and ***P < 0.0005 in comparison with untreated cells. (c) Protein levels were quantified by immunoblotting for MMP-1. The increase in protein levels in the treated cells relative to untreated cells is shown. The analysis of MMP-1 protein by Western blotting is inserted in the upper panel. Data are from a representative experiment. Bort, bortezomib; MMP, matrix metalloproteinase; TGF-β, transforming growth factor-beta; UT, untreated.