HMGB1 is essential for life: Hmgb1 knockout mice die shortly after Birth (Dumitriu et al. HMGB1: guiding immunity from within. Trends Immunol 2005, 26: 381-7). The two different activities of HMGB1 as a chemoattractanct of motile cells and as inducer of cytokines have been attributed to different biochemical forms. Fully reduced HMGB1 complete notation: HMGB1C23hC45hC106h - Antoine J.,2014) is completely reduced and has chemoattractanct activity; Disulfide HMGB1 contains a disulfide bond between C23 and C45 (complete notation: HMGB1C23-C45C106h - Antoine J.,2014) and can induce cytokine and chemokine production in monocytes and other inflammatory cells. Fully reduced HMGB1 had previously been sold by HMGBiotech as Chemotaxis-HMGB1 LPS free and tested in migration assay, but is otherwise the same identical product. Fully reduced HMGB1 behaves as a trigger of inflammation, attracting inflammatory cells, and of tissue repair, attracting stem cells and promoting their proliferation. Moreover, Fully reduced HMGB1 activates dedritic cells and promotes their functional maturation and migration to lymph nodes. However, and contrary to early reports, pure Fully reduced HMGB1 does not promote cytokine secretion. Cytokine secretion is only promoted by disulfide HMGB1 (the form containing disulfide bond). The Fully reduced HMGB1 we provide is the natural protein, with no tags or additional amino acids. It is produced in E.coli from an expression plasmid coding for the human protein. It has the sequence: