NRP1 and neoplasm: Gao et al. showed that Nrp1low CD25+ CD4+ Treg (Treg expressing low levels of Nrp1) purified from septic mice secreted lower amounts of IL-10 (17), and another study using tumor-harboring Il10KO (IL-10 deficient)-mice showed decreased Nrp1 expression in tumor-infiltrating Treg, impaired Nrp1+ Treg tumor accumulation and tumor protection function (41).