Enables JUN kinase activity and RNA polymerase II-specific DNA-binding transcription factor binding activity. Involved in several processes, including determination of adult lifespan; negative regulation of cellular response to manganese ion; and response to stress. Located in several cellular components, including axon; neuronal cell body; and nucleus. Expressed in AIYL; AIYR; and neurons. Human ortholog(s) of this gene implicated in several diseases, including Alzheimer's disease; abdominal aortic aneurysm; carcinoma (multiple); and intestinal benign neoplasm (multiple). Is an ortholog of human MAPK10 (mitogen-activated protein kinase 10); MAPK8 (mitogen-activated protein kinase 8); and MAPK9 (mitogen-activated protein kinase 9).