Since genetic depletion of Nrp1 from tumor-associated macrophages has been reported to decrease tumor growth in the periphery for pancreatic and lung tumor xenografts in mice [8], we next investigated whether CNS glioma tumor burden is different in wild type (wt) mice compared to mice with Nrp1-deficient microglia and macrophages. The gene discussed is NRP1; the disease is central nervous system cancer.