Cluster 19, termed the "IL-6-response gene" cluster, consisted of 22 genes, including Ccnb2, C5ar1, Hs3st3b1 and Id2, which were highly upregulated in microglia from GFAP-IL6 mice and mice with LPS-induced endotoxemia (Fig. 7b, Additional file 1: Fig. S11a, e), with the median log2 expression of these genes upregulated 2.1- and 1.9-fold, respectively, compared with their respective controls. Here, ID2 is linked to serum lipopolysaccharide activity.