TNFSF9 and obesity due to melanocortin 4 receptor deficiency: Meanwhile, engagement of 4-1BB (TNFRSF9) with its ligand 4-1BBL (TNRSF9) can activate the inflammatory signaling pathway involving MAP kinases in T cells and macrophages [38], and we have also shown that the 4-1BB/4-1BBL interaction on adipocytes/macrophages or muscle cells/macrophages promotes obesity-induced adipose and muscle inflammation [17, 39]; hence inflammatory receptor expression and their signaling are considered useful targets for protecting against obesity-induced inflammation [17, 39].