Dual specificity protein kinase which acts as an essential component of the JNK signal transduction pathway. May phosphorylate jnk-1 (PubMed:10393177, PubMed:15767565, PubMed:17894411). Plays a role in coordinating locomotion via D-type GABAergic motoneurons and in regulating synaptic vesicle transport downstream of adapter protein unc-16 and probably by activating jnk-1 (PubMed:10393177, PubMed:11738026). Positively regulates lifespan (PubMed:15767565). Upon environmental stress such as heat stress regulates daf-16 nuclear translocation probably by activating jnk-1 (PubMed:15767565). Regulates germline cell apoptosis in response to heavy metals such as Cu(2+) and to arsenite (PubMed:18597494, PubMed:19497412). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts with unc-16. Expressed in most neurons, including nerve ring, head ganglions, dorsal and ventral nerve cords and tail ganglions. Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. MAP kinase kinase subfamily.