A: Treatment of mBECs kept in C-SFM with cyclosporine (1,000 ng/ml) or TGF-β (10 ng/ml) for 48 hours, but not tacrolimus (1,000 ng/ml) results in up-regulation of the TGF-β receptor type II protein compared to C-SFM controls (left) as determined by Western blotting. Densitometry tracing was used to illustrate the quantitative differences (right). B: TGF-β signaling pathway is mediated by phosphorylation of the transcription factor SMAD-2. In this Western blot (left), total cellular protein was probed for phospho-SMAD-2, which was detected in the mBECs treated with cyclosporine (1,000 ng/ml), but not with tacrolimus (1,000 ng/ml). The positive control consisted of mBECs treated with 10 ng/ml of exogenous TGF-β. Densitometry tracing was used to illustrate the quantitative differences (right). C: In this Western blot, BEC nuclear protein was probed for the cyclin-dependent kinase inhibitor protein, p21WAF1/Cip1, which is elevated 48 hours after treatment with either TGF-β (10 ng/ml; positive control) or cyclosporine (1,000 ng/ml), but not in the control C-SFM or after treatment with tacrolimus (1,000 ng/ml).