To further examine the possible role of stress signaling pathways in obesity,aging and leptin-induced cardiac responses, expression of p38 MAP kinase, JNK,ERK and the NFκB inhibitor IκB as well as their phosphorylationwere examined in young and aging C57 lean and ob/ob mousecardiomyocytes. The gene discussed is MAPK8; the disease is obesity due to melanocortin 4 receptor deficiency.