RETN and obesity due to melanocortin 4 receptor deficiency: In the present study, we examined the in vitro effects of 24 h exposure to high concentrations of insulin, leptin, and glucose, commonly seen in obesity and type 2 diabetes, on the mRNA expression and protein secretion of resistin, TNF-α, IL-6, and IL-1β from human peripheral blood monocyte-enriched mononuclear cells.