The proteins act to specifically target the claudin-3 and claudin-4 epithelial receptors present in breast, prostate, lung, endometrial, thyroid, and pancreatic cancer tumors. The carboxy-terminal fragment of the CPE bacteria has a high-affinity to certain cell receptors, such as claudin-3 and claudin-4 cell receptors which are heavily present in the previously listed tumors. In the future, CPE could potentially be used in two ways. For one, physicians have potential to detect residual amounts of disease by coupling radioactive isotopes to the CPE. This is a very effective way to locate minor metastasized parts of cancer throughout a patient’s body. The second method is that CPE can be used is by coupling anticancer agents to it, which CPE would deliver directly to the tumor for therapeutic