SERPINE1 and ovarian cancer: Additionally, in order to test whether the compound truly works as a PAI-1 inhibitor of uPA, the enzymatic activity of uPA was assessed by casein-plasminogen zymography in three ovarian cancer cell lines, SKOV3ip1 (PAI-1 positive), HeyA8 (PAI-1 positive) and OVCAR3 (PAI-1 negative) (Supplementary Figure 1B).