NFKB1 and obesity due to melanocortin 4 receptor deficiency: Obesity-associated FFAs induce inflammation via TLR4, the receptor for lipopolysaccharide (LPS) that plays a critical role in initiating intracellular nuclear factor-kappaB (NF-κB)-mediated signaling, leading to activation of innate immunity (112) and causing IR in AT (93) (Fig. 2).