The goal of the present study was to test the hypotheses that: 1) JNK inhibition will be antinociceptive on its own; 2) JNK inhibition will augment morphine antinociception and; 3) JNK mediates chronic tolerance for the antinociceptive effects of morphine using acute (hotplate and tail-flick), inflammatory (10 μl of formalin 2.5 %) and chemotherapy (cisplatin 5 mg/kg ip once weekly)-induced neuropathic pain assays. The gene discussed is MAPK8; the disease is neuropathic pain.