Figure 8.

TGF-β1 activation of PI3K/AKT is independent of ET-1. IMR-90 fibroblasts were transfected with pooled small interfering RNA (siRNA) targeting ET-1, the ET-A receptor, the ET-B receptor, or with a nontargeting (NT) siRNA. (A) At 72 hours after transfection, RNA was isolated from the transfected cells for quantitative real-time PCR for ET-1, ET-A, or ET-B to demonstrate that there was significant knockdown of the targeted mRNA. (B) Similarly transfected IMR-90 fibroblasts, or nontransfected fibroblasts, were treated with/without TGF-β1 (2 ng/ml) for 16 hours, and AKT phosphorylation was assessed by Western immunoblotting. Membranes were stripped and probed for total AKT. Results are representative of three separate experiments.