Collagenase activity in media derived from normal, desmoid fibroblasts and desmoid fibroblasts plus toremifene. Panel A. NF: normal fibroblasts; DF: desmoid fibroblasts; DFT: desmoid fibroblasts plus toremifene. Similar results were obtained in four separate experiments. In panel B the quantity of 3/4 and 1/4 fragments of digested collagen was determined by densitometric analysis. The absolute counts were converted to percentages assuming the level of normal fibroblasts as 100%.