It promotes insulin resistance by the inhibition of the insulin receptor substrate 1 signaling pathway and also induces adipocyte apoptosis Although elevated levels of TNF-α, IL-6 and IL-1 are observed in the adipose tissue in conditions of obesity, only TNF-α concentrations are increased in the adipocytes [49]. This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.