PTGS2 and obesity due to melanocortin 4 receptor deficiency: As an inflammatory state characterizes obesity and IR, we evaluated the gene expression of cyclooxygenase-2 (COX-2), TNF-α, IL-6, nuclear factor kappa B (NF-κB) and inhibitor of kappa B (IκB) by RT-qPCR in the liver (Figure 3A–E).