Plasminogen activator secreted by cultured human melanocytes

SUMMARY A plasminogen activator (PA), Mr 72 000, was detected in conditioned medium from human melanocyte cultures by fibrin autography. The electrophoretic mobility was identical to that of tissue PA produced by Bowes melanoma cells. PA activity in human melanocyte culture medium was inhibited by anti‐tissue PA IgG, but not by anti‐urokinase IgG. Our results are the first to show that normal human melanocytes in culture secrete tissue plasminogen activator.