Cytokine induced pancreatic beta-cell destruction seen in Type 1 diabetes and islet graft rejection involves multiple intracellular signaling pathways that directly or indirectly lead to inflammatory damage or programmed cell death. IL-1beta has been shown to stimulate the 12-lipoxygenase pathway product 12-HETE, in RIN m5F cells; however, the precise role of 12-LO activation in mediating cytokine effects is not clear. Since the stress-activated protein kinase, JNK, has been linked to cytokine mediated inflammatory actions, we studied the effect of two LO products, 12-HETE and 15-HETE, on JNK activity. We demonstrate that 1 nM 12-HETE stimulates JNK activity, while 1 nM 15-HETE, the 15-lipoxygenase pathway product, does not. These results suggest 12-HETE is a novel upstream signal for IL-1beta induced JNK activation in RIN m5F cells.