S100A9 and gingivitis: Based on these results, our group speculated that the glutathionylation in S100-A9 may result in a protective effect against oxidative process at the site of inflammation thus providing a coherent explanation to the observed reversed ratio between the m/z = 13,458 (both glutathionylated and acetylated) and the m/z = 13,153 (acetylated only) forms of S100-A9 peptide in gingivitis patients compared to healthy subjects [24].