S100A9 and Sepsis: S100A9 protein phosphorylation and dimerization with S100A8 and subsequent secretionrequire phosphorylation on S100A9 by p38 MAPK (32, 33) and activation of PKC in aCa2+-dependent manner (16).Our results showed that S100A9 protein phosphorylation and dimerization were inhibitedin the Gr1+CD11b+ cells from late, but not early,septic mice despite normal activation of p38 and PKC throughout the sepsis course.