ABCB1 and pancreatic cystadenoma: Corresponding formalin-fixed paraffin-embedded (FFPE) sections of our study groups with 91 patients with PDAC UICC stage II and 13 patients with pancreatic cystadenoma or papillary adenoma (total n = 104) were evaluated immunohistochemically by tissue microarray for the expression of the tumor suppressor PTEN, the gemcitabine metabolism regulators DCK and HuR, and the ATP transporters MDR-1, MRP-1, and BCRP-1, as well as the tumor angiogenesis marker vascular epithelial growth factor (VEGF)-1.