Exosomes from MDA-MB-231 cells can increase the plasmin generation of tumor cells. Exosomes were collected from MDA-MB-231 cells and incubated with MCF7 and A549 cells for 2 hours. Subsequently, tumor cells were seeded at 50 000 cells per well for 3 days. Cells were tested for plasmin generation with plasminogen at 0.5 μM final concentration and the substrate S2251 at 0.5 μM final concentration. OD was read at 405 and 600 nm for 4 hours every 4 minutes at 37°C. The experiment was repeated 3 times in triplicate. Results show the rate of plasmin generation per 1 million cells. Cells with no incubation of exosomes are represented by the red bars, and cells with incubation of exosomes are represented by blue bars. *P < .05, Mann-Whitney U test (1 tailed).