S100A9 and infection: Genes in Cluster 2 (376 genes) were specifically upregulated in Group B and included genes related to cell migration (SELL, ITGAM), inflammatory response and response to infection (FCGR1A, FCGR1B, CAMP, S100A9, S100A12, S100P, MPO, TNFSF4, PADI4, CHI3L1, MARCO; GO:0042742, GO:0045087), cell cycle, and negative regulation of myeloid cell differentiation (MKI67, CDC14B, HIST1H3D, HIST1H3J, LILRB1; GO:0007049; GO:0045638).