Figure 3. TGZ decreases TGFβ2-induced expression of fibronectin and collagen type I mRNA in ARPE-19 cells.ARPE-19 cells were either left untreated or were treated with 4 ng/ml TGFβ2 for 24 h, or were pretreated with 10 μM TGZ, DMSO (0.05%), 10 ng/ml Actinomycin D, or 10 μM SB203580 for 1 h and then incubated with TGFβ2 for additional 24 h. Total RNA was extracted, and RT–PCR analysis for fibronectin and collagen type I (COLI) was performed. Glyceraldehyde-3-phosphate dehydrogenase (G3PDH) expression was examined for normalization purposes. Experiments were repeated twice and the results were reproducible.