Modulation of cell proliferation by protein proteinase inhibitors. A new analytical approach

Human alpha 1-proteinase inhibitor (alpha 1-antitrypsin) and bovine pancreatic trypsin inhibitor both inhibit cell-surface proteolytic activity in human fibroblasts. At the inhibitory concentrations, these proteins also inhibit cellular proliferation, as assayed by a microassay based on spectrophotometry of fixed and stained cells. Despite testing a wide range of proteinase inhibitor concentrations, no evidence was found for mitogenic or growth-stimulatory activity. ovomucoid was inactive against cell-surface proteinase activity and did not inhibit cellular proliferation.