S100A9 and glioblastoma: Finally, to determine the inflammatory process associated with the expression of S100A9, we defined an inflammation gene signature composed of those genes co-expressed with S100A9, which were implicated in inflammatory processes (TCGA GBM cohort) and upregulated in the hypoxic and necrotic tumor areas (IvyGAP) (Figure 4H), called hypoxic inflammation signature.