To assess the clinical importance of PAI-1 in tumor evolution, an IHC assay was performed to detect the levels of PAI-1 in 90 primary and 17 metastatic melanoma samples and 50 tumor samples (45 TNBC vs. 5 non-TNBC) and sorted them into low, medium, and high PAI-1 expression groups (Fig. 8A, C). This evidence concerns the gene SERPINE1 and metastatic melanoma.