For example, Zhang et al. found that the adipose tissues of insulin-resistant and non-insulin-resistant patients with obesity had differential expression of a number of genes, including matrix metallopeptidase 9, interleukin (IL)6, C-X-C motif chemokine ligand (CXCL) 8, C-C motif chemokine ligand 4, and CXCL10, which are enriched for several functions, including cytokine-cytokine receptor interactions, tumor necrosis factor (TNF) signaling, and pathways in cancer (Zhang et al., 2019). Here, TNF is linked to obesity due to melanocortin 4 receptor deficiency.