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. Here, APLN is linked to obesity due to melanocortin 4 receptor deficiency.