Serine/threonine kinase which responds to activation by environmental stress and pro-inflammatory cytokines by phosphorylating downstream targets (PubMed:11703092, PubMed:12142542, PubMed:16166371, PubMed:18394898, PubMed:22308034, PubMed:20369020). As part of a MAP kinase signaling pathway, plays a role in modulation of lifespan and immunity (PubMed:29748542, PubMed:12142542, PubMed:20369020, PubMed:22216003). Phosphorylates skn-1 which probably regulates skn-1 nuclear translocation in response to oxidative stress (PubMed:16166371). Probably by activating skn-1, involved in the up-regulation of gcs-1 and glutathione-S-transferase gst-4 expression upon bacteria infection (PubMed:22216003). Up-regulates expression of gcs-1 in intestinal cells upon arsenite treatment (PubMed:16166371, PubMed:25204677). Functions downstream of the MAPKK sek-1 and the MAPKKK nsy-1 as the MAP kinase which regulates pathogen resistance and responses to oxidative stress (PubMed:11703092, PubMed:12142542, PubMed:16166371, PubMed:18394898). Required for expression of antimicrobial peptide nlp-29 in response to fungal infection or physical injury (PubMed:18394898). Involved in resistance to the nematotoxic C.cinerea galectin (Cgl2) (PubMed:20062796). May play a redundant role with other MAP kinases in susceptibility to anoxia, downstream of tir-1/nsy-1 (PubMed:21212236). Phosphorylates transcription factor rnt-1 during oxidative stress which results in rnt-1 stabilization in the intestine (PubMed:22308034). Phosphorylates transcription factor atf-7 during pathogen infection resulting in modulation of target genes (PubMed:20369020). Probably downstream of nsy-1 and sek-1, involved in germline apoptosis induced by heavy metals, such as Cu(2+) (PubMed:19497412). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Divalent cations such as magnesium or manganese. Activated by phosphorylation on threonine and tyrosine. Inhibited by pyridinyl-imidazole related compounds. Interacts with transcription factor atf-7; perhaps in a manner dependent on dual specificity protein kinase sek-1. Accumulates in nucleus in response to heavy metals, such as cadmium. Expressed in intestinal cells. The TXY motif contains the threonine and tyrosine residues whose phosphorylation activates the MAP kinases. Dually phosphorylated on Thr-191 and Tyr-193, probably by sek-1, which activates the enzyme (PubMed:16166371, PubMed:21212236). Increased phosphorylation in response to the heavy metal arsenite (PubMed:25204677). Increased phosphorylation in response to intestinal colonization by probiotic Lactobacillus fermentum strain JDFM216 (PubMed:29748542). Knockout causes reduction in adult lifespan (PubMed:29748542). Upon infection by P.aeruginosa or E.faecalis, RNAi-mediated knockdown results in a decrease in survival rate and in a reduced up-regulation of gst-4 and gcs-1 expression (PubMed:12142542, PubMed:22216003). Causes a severe reduction in rnt-1 accumulation in the intestine during oxidative stress mediated by paraquat (PubMed:22308034). Upon exposure to C.cinerea galectin Cgl2, adults show reduced survival and larvae do not develop (PubMed:20062796). Larval development is partially restored in a bre-1, fut-8, gly-13, galt-1 or ger-1 mutant background (PubMed:20062796). Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MAP kinase subfamily.