RARRES2 and obesity due to melanocortin 4 receptor deficiency: In human GC, different adipokines, such as adiponectin, visfatin, omentin, and apelin, enhanced IGF1-induced E2 synthesis, while resistin and chemerin seemed rather to act as negative regulators of steroidogenesis [58], so the effect is linked more with properties of the studied adipokine than its levels in serum or FF, which differ between obesity and PCOS.