SERPINE1 and neoplasm: Nevertheless, and with these limitations in mind, we still believe that the results are solid, since the interaction of progesterone receptor- and uPA–PAI-complex-positivity has been tested from every possible angle, and, asTable 4 clearly shows, there seem to exist huge biological differences in relation to the expression or not of progesterone receptors by the tumours, especially in association with the expression of uPA–PAI complexes by them.