To further explore the potential usefulness of the S100A4 protein as a plasmatic biomarker for diagnosis, we quantified the levels of S100A4 in plasma samples obtained from four different xenograft tumor models (MiaPACA-2, MDA-MB-231 from breast adenocarcinoma, and Colo205 and HCT116 from colon carcinoma cell lines). This evidence concerns the gene S100A4 and breast adenocarcinoma.