NOS2 and neoplasm: However, during cancer progression, the accumulation of inducible nitric oxide synthase positive (iNOS+) and CD11b+Gr1+ myeloid cells in the peritumoral region suppresses the contraction of tumor-draining collecting lymphatic vessels (117) (Figure 1), which might diminish tumor antigen transportation and DC trafficking to the TDLNs, reducing the immune response (118).