GROWTH-RELATED PROTEINASES IN CULTURED HUMAN TUMOR-CELLS

The proliferation of normal cells, and of early-passage cells from tumours, is inhibited as a consequence of inhibition of a cell-surface proteinase activity. In contrast, established tumour cell lines are usually resistant to these effects. It has previously been suggested that the change from sensitivity to resistance may be a consequence of tumour progression, but experiments with an additional three human tumour cell cultures show that this change is not inevitable.