MAPK3 and infection: In the genus of Edwardsiella, there is another pathogen—Edwardsiella ictaluri, which mainly infects catfish and zebrafish, and its invasion activates extracellular signal-regulated kinases 1 and 2 (ERK1/2) early in infection, which are subsequently inactivated by its T3SS effector EseN through dephosphorylation, resulting in increased proliferation (17, –, 19).