The Multidrug Resistance Protein ABCC11/MRP8 is expressed in physiological barriers and tumor breast tissues in which it secretes various substrates including cGMP (cyclic guanosine monophosphate) and 5FdUMP (5-fluoro-2′-deoxyuridine-5′-monophosphate), the active metabolite of the anticancer drug 5-FluoroUracil (frequently included to anticancer therapy). The gene discussed is ABCC11; the disease is neoplasm.