Histology of pancreatic tumors from the Syngeneic Tumor Implantation Model (STIM) confirms adenocarcinoma with a formation of glands and b regions of desmoplasia (arrowhead). The histology is comparable to that observed in c tumors from genetically engineered KPC mice. Immunohistochemistry demonstrates that pancreatic tumors from STIM mice stain for d cytokeratin-19/CK-19, a ductal epithelial marker (CK-19 in brown, methyl green counterstain, 40×). Hematoxylin and eosin staining of liver (e) and peritoneal metastases (f) from STIM mice confirms adenocarcinoma. STIM tumors are infiltrated with g distinct immune cell populations of CD4 helper T cells, CD8 cytotoxic T cell, macrophages, and myeloid-derived suppressor cells (MDSCs)