Figure 5

TGF-β1 induces the production of MMP-9 by J3B1A cells. (A) Western blot analysis of conditioned media from J3B1A cells incubated with 50, 200 and 1000 pg/ml TGF-β1 for 72 hours. MMP-9 is induced by TGF-β1 in a dose-dependent manner. MMP-13 and MT1-MMP (MMP-14) are constitutively expressed by J3B1A cells and are not ostensibly modulated by TGF-β1. Conditioned medium from PMA-treated human U937 cells was used as a positive control for MMP-9, and conditioned medium from SVEC4-10 cells as a control for MMP-13 and MMP-14. Uniform loading of lanes was verified by silver staining. The blots shown are representative of at least two independent experiments. (B) Gelatin zymography of conditioned media from J3B1A cells incubated with 50, 200 and 1000 pg/ml TGF-β1 for 72 hours. TGF-β1 induces the secretion of MMP-9 in a dose-dependent manner, a clear increase in MMP-9 activity being already evident at 50 pg/ml TGF-β1. Conditioned medium from PMA-treated U937 cells, which are known to produce MMP-2 and MMP-9, was used as a positive control.