NFKB1 and obesity due to melanocortin 4 receptor deficiency: The interaction of Fn14/TWEAK increases activation of NF-κB signaling and proteolytic pathways such as the ubiquitin-proteasome system [9], and this is accompanied by reduction of mitochondrial oxidative metabolism and fiber type switching in skeletal muscle [11, 12], indicating that the inflammatory receptor/ligand system participates in obesity-induced muscle atrophy and metabolic dysregulation as well.