XBP1 and infection: Previously, we established that the ER stress induced by exposure to P. aeruginosa, as well as the lethality of the xbp-1 mutant during infection by P. aeruginosa, are suppressed by a loss-of-function mutation in pmk-1, which encodes a conserved p38 mitogen-activated protein kinase (MAPK) that regulates innate immunity in C. elegans[27].