Soluble NRP-1 (sNRP-1) can be successfully quantified using ELISA-based approaches (Lu et al. 2009) and more recently, plasma and tumor tissue levels of NRP-1 were found to be upregulated in node-positive patients with BC and advanced metastatic disease (Naik et al. 2017). This evidence concerns the gene NRP1 and metastatic neoplasm.