A polypeptide secreted by transformed cells that modulates human plasminogen activator production.

A diffusible factor produced and secreted by malignant murine cells was capable of inducing plasminogen activator production by normal diploid human fibroblasts. The factor's ability to induce plasminogen activator was insensitive to treatment with nucleases, but its activity was destroyed by digestion with proteases. It is proposed that such a factor would play a role in malignancy if it would recruit normal cells that were adjacent to transformed cells to produce plasminogen activator which could result in tumor-promoted proteolysis.