A second pathway of HMGB1 nuclear/cytoplasmic shuttling has been reported involving phosphorylation, 33 mediated by protein kinase C. 36 In neutrophils, HMGB1 is post-translationally methylated, which alters its conformation and weakens its DNA-binding activity, causing its cytoplasmic localization. 34 Recently, HMGB1 has been shown to undergo oxidation that may have the potential to modulate various aspects of its function, including subcellular localization, interaction with DNA, cytokine activity and proinflammatory activity. 37 Indeed, induction of immunological tolerance by apoptotic cells was shown to require caspase-dependent ROS production by mitochondria, which oxidized the danger signal HMGB1, and thereby neutralized its damage-associated molecular pattern molecule (DAMP) function, including the ability to activate DCs. 38 From the reverse perspective, in necrotic cells that do not generate ROS and provide fully active HMGB1, treatment with H 2 O 2 inactivates the DAMP function of the protein. Thus, DAMP is released and can work, but briefly and in a short range, until it gets oxidized. This restricts its activity temporally and spatially, preventing a prolonged stimulation of its targets and thereby limiting inflammation. 39 HMGB1 is essential for DC maturation, migration and Th1 polarization. Inflammatory signals activate antigenpresenting DCs, which undergo a differentiation process referred to as maturation and migrate to secondary lymphoid organs. HMGB1 has a crucial role in this process, acting as a chemoattractant for immature DCs (iDCs) that involves RAGE, and further inducing DC maturation, as shown by the upregulation of the surface markers CD80, CD83, CD86 and human leukocyte antigen (HLA)-A, B, C, and DC production of cytokines, including IL-6, CXCL8, IL-12p70 and TNF-a. 11, 40 The mobilization of DCs from peripheral tissues is critical for the establishment of T-cell-dependent immune responses or tolerance, because the physical interaction of DCs with naive T cells takes place in the T-cell areas of lymph nodes. Importantly, in vivo homing of DCs to draining lymph nodes depends on RAGE, 41 a finding consistent with the in vitro upregulation of the CCR7 and CXCR4 receptors upon autocrine secretion of HMGB1 by mature myeloid DCs. 40 Thus, the autocrine/paracrine release of HMGB1 and the integrity of HMGB1/RAGE pathway are required for the migratory function of HMGB1. Moreover, HMGB1 secreted by DCs is required for clonal expansion, survival and functional Th1 polarization of naïve T cells, which occurs through the secretion of proinflammatory cytokines, including IL-12, IL-18 and IFN-g 42, 43, 21 In the presence of inhibitors of HMGB1 or of RAGE, DC activated with pathogen-associated molecular patterns (PAMPs) fail to mature 43 ( Figure 2 ).