Fig. 3. Growth factors increase the level but not the activation status of proteinases secreted by primary mammary organoids. Mammary organoids were treated for 4 to 6 days in collagen I gels with no growth factor (No GF) or with EGF, HGF, bFGF or KGF. Conditioned medium was collected, concentrated and run on substrate zymograms. (A) Gelatin zymogram. Latent gelatinase B (LGB), active and latent gelatinase A (AGA, LGA) and a high molecular weight gelatinase (HG) were detected. (B) Casein zymogram. A band corresponding to the molecular weight of latent stromelysin-1 (LStr1) was detected. (C) Plasminogen casein zymogram. A band corresponding to the molecular weight of uPA was detected. There were no differences in the activation status of the gelatinases, caseinase or plasminogen activator between growth factor treated organoids and untreated controls.