UPA and LRP1 expression in bladder and breast cancer cell lines. (A) Skin fibroblasts, bladder and breast cancer cell lines respectively resembling different stages (RT4 -T1 superficial-, RT112 and 5637- T2 muscle invasive-, HT1376 and ECV304 -T3 muscle invasive-) and subtypes (MDA-MB-468, MDA-MB-231, BT549, SUM149, SUM159 -TNBC-, SKBR3 -HER2+-) were analyzed by qPCR for UPA gene expression (see “Materials and Methods”). (B) Competition assay between ATF-SAP and uPAR natural ligands. MDA-MB-468 cells were incubated with ATF-SAP 20 nM in the presence of equal or increasing concentrations of uPA or PAI. The effect on cell viability was evaluated after 72 h by MTT assay. Seed SAP was used as untargeted control. (C) Comparison of pro-uPA-SAP and ATF-SAP toxic activity on fibroblasts and MDA-MB-231 cells. Results from one representative experiment are shown as mean ± SD. Three independent experiments were performed for each assay. LRP1 gene (D) and protein (E) expression on bladder and breast cancer cells. LRP1 protein expression is displayed as histogram plots (E, left panel) and RFI (see “Materials and Methods”) (E, right panel). The dashed line represents the threshold arbitrarily defining positive expression (RFI = 2).