B A n=3 n=2 Effect of cancer cell-conditioned media (CM) on TGF-b activation and on fibroblast b-gal activity. A) 5PT or IC6PR cells were cocultured for 24 hours with MLEC cells stably expressing a TGF-β1-responsive luciferase reporter construct. 5PT CM stimulated luciferase activity, whereas activity in IC6PR/MLEC coculture remained at basal level. 0.25ng/ml TGFb is included as a positive control. B. HFFF2 cells were treated for 12 days with TGFb1 (2ng/ml) and conditioned media from 5PT or IC6PR, with or without TGFb Receptor I Kinase Inhibitor (1uM; Calbiochem). 5PT CM and TGFb induced fibroblast bgal expression which was suppressed by the kinase inhibitor, confirming that this was modulated by TGF-b1. Consistent with the inability to activate TGF-b1 (A), IC6PR CM did not induce fibroblast bgal.