Figure 1. Intratumoral low-dose tumor necrosis factor α (TNFα-RGR, TNFα conjugated with vascular homing peptide, injected i.v.) increases tumor vessel stability and vascular perfusion. Remodeled vessels are highly activated and express VCAM, vascular cell adhesion molecule (VCAM). Tumor resident macrophages switch from a M2 to a M1 phenotype, express high levels of VCAM, monocyte chemotactic protein 1 (MCP1), interleukin 6 (IL-6), inducible nitric oxide synthetase (iNOS) and angiopoietin 2 (Ang2), and cluster around tumor vessels. Adoptively transferred antitumor T cells are unable to penetrate into untreated tumors, but infiltrate tumors after “pre-conditioning” with TNFα, which leads to tumor regression.