In our recent work treating murine pancreatic cancer, we used immunohistochemistry to label sections of rechallenge tumors with anti-CD8 antibodies and showed that the concentration of CD8+ cells was much higher in tumors injected into mice whose primary tumor was treated with NPS than in those in which the primary tumor had been removed surgically.21 This provides additional evidence that NPS treatment stimulates an antitumor immune response. This evidence concerns the gene CD8A and familial pancreatic carcinoma.