Malinowsky, K et al. [47]evaluated the roles of uPA and PAI-1 in thePI3K/AKT and MAPK pathways in the primary tumors and metastases of breast cancer, and the results illustrate that there is good correlation between uPA and p38/MAPK in tumors and metastases, and these results demonstrate that uPA is involved in cancer invasion and metastasis partially through the activation of the p38/MAPK pathway. Here, PLAU is linked to breast cancer.