Upon pathogen infection, C. elegans can mount protective responses by triggering evolutionarily conserved innate immune signaling pathways, such as the PMK-1/p38 mitogen-activated protein kinase (MAPK) pathways, the DBL-1 pathway [homologous to the mammalian transforming growth factor–β (TGF-β) cascade], and the unfolded protein response (UPR) (24–26). This evidence concerns the gene MAPK14 and infection.