Scaffold protein which plays an important role in the activation of the JNK pathway composed of mlk-1, mek-1 and kgb-1; by bringing together mek-1 and mlk-1, promotes mlk-1-mediated phosphorylation and activation of mek-1 which in turn phosphorylates kgb-1 (PubMed:18832074, PubMed:18809575). In addition, negatively modulates the activation of the insulin/IGF-1-like signaling (IIS) probably by inhibiting the insulin receptor daf-2. Positively regulates the activity of the transcription factor daf-16/FOXO by both inhibiting IIS and activating the JNK pathway (PubMed:18832074). Involved in the response to several environmental stresses including heavy metal ions (Cu(2+) and Cd(2+)), heat, oxidative and protein misfolding (ER) stresses (PubMed:18832074, PubMed:18809575). Plays a role in life span and egg laying (PubMed:18832074, PubMed:23072806). Plays a role in axon regeneration after injury (PubMed:23072806, PubMed:27984580). Interacts (via PID domain) with daf-2 (via cytoplasmic domain) (PubMed:18832074). Interacts with mek-1; the interaction is independent of mek-1 catalytic activity and is constitutive (PubMed:18832074, PubMed:18809575). Interacts (via N-terminus) with mlk-1 (via NPQY motif when phosphorylated on tyrosine residue) (PubMed:18809575, PubMed:23072806). Does not interact with jkk-1 or sek-1 (PubMed:18809575). Interacts (via SH2 domain) with svh-2 (PubMed:27984580). Interacts with svh-4 (PubMed:27984580). In intestinal cells, enriched in the nucleus. Expressed in hypodermis, intestine, head and tail neurons, pharynx, gonads, vulva and body muscles.