The effects of MCF-7 breast adenocarcinoma CM on MMP and TIMP activity from THP-1 monocytes. (a) Gelatin zymogram and (b) MMP-2 immunoblot showing the upregulation of monocyte MMP-2 after exposure to MCF-7 CM, and (c) a reverse zymogram to show that the activity of monocyte TIMP-1 and -2 remained the same upon treatment. Lanes 1, 4, and 7 contain CM from THP-1 cells in serum-free media grown in the presence of 100 μl, 200 μl and 300 μl concentrated MCF-7 CM, respectively. Lanes 2, 5, and 8 contain CM from THP-1 cells in serum-free media grown in the presence of 100 μl, 200 μl and 300 μl concentrated serum-free media, respectively. Lanes 3, 6, and 9 contain serum-free media with 100 μl, 200 μl and 300 μl, respectively, of MCF-7 CM in the absence of THP-1 cells. These figures are representative of three independent experiments carried out in duplicate, each of which demonstrates similar results.