The weakly pathogenic E. coli only activated the upregulation of midstream Nsy-1 and Sek-1, and did not activate the expression of Pmk-1 and Skn-1, indicating that Nsy-1 and Sek-1 are more sensitive in response to E. coli infection, which is consistent with the result of Dennis’ screening of Nsy-1 and Sek-1, two pathogen resistance genes, from a variety of nematode mutants with increased susceptibility to P. aeruginosa lethality, suggesting that both are essential genes for resistance to pathogenic bacteria and play an important role in resistance to pathogen infection [53]. This evidence concerns the gene MAP2K4 and infection.