PLAUR and neoplasm: Of note, both plasma levels of human uPAR (secreted by human MDA-MB-231 TNBC cells) and mouse uPAR (secreted by the host) were elevated in the MDA-MB-231-bearing NSG mice as measured by human uPAR and mouse uPAR ELISA kits, respectively (Figure 3E), indicating that in addition to tumor cells, the host cells also secrete uPAR, contributing to the elevated plasma levels of uPAR.