Quantification of circulating fl-OPN in plasma from breast cancer patients compared to normal healthy volunteers. A) Our newly developed ELISA (MAbs 2F10 and 1F11) were used to quantify plasma fl-OPN levels in fifty healthy volunteers (normal) versus forty patients with metastatic breast cancer (Stage IV). A significant increase was found in the cancer patient population. Graphed are means ± SEM. The same samples from normal volunteers or patients with metastatic breast cancer were quantified using the different fl-OPN assays, and graphed as means ± SEM. Note the different y-axis scales. The data are shown individually as well to reflect the range of values (B).