In human cells, YopJ (a HopZ-related effector from the human plague pathogen, Yersinia pestis) acetylates the activation loops of MAP kinase kinases (MEK2, MAPKK6) and both the α and β subunits of the IκB kinase (IKK) complex, resulting in inhibition of MAP kinase and NF-κB signaling pathways [47,48]. This evidence concerns the gene NFKB1 and plague.