The article presents the study on epigenetic effector used by bacterial pathogens to interfere with host signalling pathways. An overview of the study by Arbibe and colleagues of Shigella flexneri that inhibits the transcription of nuclear factor (NF)-KB-regulated genes by preventing histone H3 phosphorylation, the interaction of S. flexneri with the host cell mitogen-activated protein kinase (MAPK) signalling pathways, and the characteristics S. flexneri OspF type III effector, is presented.