PCNA and neoplasm: IHC staining of pancreatic head and tumor sections showed that pERK (a KRAS activation effector), PCNA (a proliferative marker), CK19 (a ductal origin marker), E-cadherin (an epithelial lineage marker), and vimentin (a mesenchymal marker) were expressed in the tumor stroma (Fig. 6a, b), indicating that PDAC had developed in the DIC pig.