Although the metastasis of breast cancer cells is a complex process that requires the activity of multiple genes including urokinase plasminogen activator, cytokines, chemokines, and matrix metalloproteinases (MMPs) [27], [28], [29], it has been widely reported that the selectin family of adhesion molecules and their ligands play a critical role in tumor cell metastasis through blood vessels [1], [2], [3]. Here, PLAU is linked to breast cancer.