Fig. 5. Pancreatic stellate cells promote invasion and growth of pancreatic tumors in the CAM model and a xenograft model in nude mice. (A) If CAMs of chick embryos were inoculated with Panc1 cells alone, after 4 days no invasion of the membrane was observed by microscopic examination of hematoxylin-eosin-stained paraffin sections. In combination with human PSC, Panc1 cells formed significant tumors in all cases and markedly invaded the CAM. Initial magnification was 200x. (B) After subcutaneous injection of tumor cells into nude mice either alone on the right-side or in combination with PSC on the left-side, palpable tumors formed at the site of injection in all cases after 11 days. Tumor weight of explanted pancreatic tumors induced by subcutaneous injection of Panc1, MiaPaCa2 or SW850 either in the presence (+PSC) or absence (-PSC) of PSC in nude mice was determined at the end of the experiment. The squares represent the mean, the circles the single measured values, the boxes the standard error and the error bars the standard deviation observed for six animals. All groups with PSC were significantly larger than the respective group without PSC (^*P<0.05).