Specifically, histological sections of pancreatic carcinomas from CCR4−/− mice showed 0.14 ± 0.02% of F4/80+ area compared to sections of tumors from C57BL/6 wildtype mice, which showed 0.39 ± 0.06% macrophage staining in sections from pancreatic cancer-bearing wildtype C57BL/6 mice (p = 0.002). The gene discussed is CCR4; the disease is exocrine pancreatic carcinoma.