In accordance with the results shown in Figure 1 CCR2−/− mice bearing CCR2+/+ tumor cells did not differ in tumor size from control WT mice (Fig. 4A), yet they displayed a significantly decreased luciferase activity (Figure 4B, C, 7.31±1.4 compared to 1.69±0.35, p<0.01). The gene discussed is CCR2; the disease is neoplasm.