Catalytic domain of the Serine/Threonine Kinase, c-Jun N-terminal Kinase 3STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. JNK3 is expressed primarily in the brain, and to a lesser extent in the heart and testis. Mice deficient in JNK3 are protected against kainic acid-induced seizures, stroke, sciatic axotomy neural death, and neuronal death due to NGF deprivation, oxidative stress, or exposure to beta-amyloid peptide. This suggests that JNK3 may play roles in the pathogenesis of these diseases. JNKs are mitogen-activated protein kinases (MAPKs) that are involved in many stress-activated responses including those during inflammation, neurodegeneration, apoptosis, and persistent pain sensitization, among others. The JNK3 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.