Figure 6.

Plasminogen-induced fibroblast apoptosis is not mediated by MMPs. IMR-90 fibroblasts were treated with/without plasminogen (50 μg/ml) ± TGF-β1 (2.0 ng/ml) and/or the broad-spectrum MMP inhibitor BB2516 (5.0 μM) for 18 hours. (A) Cell culture supernatants were assessed for plasmin activity. n = 4; *P < 0.001 versus controls, **P < 0.001 versus plasminogen alone. (B) Cell culture supernatants were assessed for fibronectin by Western immunoblotting. (C) Apoptosis was assessed using ELISA for ssDNA. n = 4; *P < 0.001 versus control, **P < 0.001 versus plasminogen. (D) Apoptosis was also assessed by Western immunoblotting of whole cell lysates for cleaved caspase-3. Blots were stripped and probed for GAPDH. All data represent experiments performed at least three times.