Many human tumors, such as those that arise in the pancreas, once detected, are very difficult to treat successfully due to their advanced stage on discovery. Therefore, there is a real need to develop an efficacious, simple and relatively non-invasive clinical assay to detect malignant tumors at an early stage. This project was designed to find a potential clinical biomarker that can identify early stage tumors based on the hypothesis that cancers originate from adult human stem cells, which ultimately give rise to “cancer stem” cells. Previous studies in our laboratory have shown that normal human adult stem cells, including those from pancreas and breast, express a transcription factor, named Oct4A. Because Oct4A is a nuclear-located protein, and is not secreted into body fluids, it cannot be used as a clinical biomarker with current non-invasive technologies. The glycoprotein, Mannitou, which is expressed by pancreatic stem cells, could, however, serve as a clinical biomarker if it can be shown to be co-expressed with Oct4A and if it is found in the body fluids in future clinical assay of patients, with and without pancreatic cancer. Therefore, preliminary studies were carried out to determine whether this glycoprotein was co-expressed with Oct4A in both normal and cancer stem cells. Using antibodies specific to each protein, both normal and cancer pancreatic and breast cells were examined for the expression of Oct4A and Mannitou. While these two proteins appear to be co-expressed in these cells in vitro, further studies on normal and cancerous human tissues in vivo must be carried out. If confirming the hypothesis, future studies will have to include development of sensitive clinical ELISA assays to detect the Mannitou glycoprotein in banked samples of serum of humans who eventually developed cancer and those who did not. Research was supported by MSU grant 08-IRGP-1538.