FOXO1 and obesity due to melanocortin 4 receptor deficiency: The PI3-K/AKT signaling pathway activated by IL-6 regulates cellular functions that relate to the development of obesity and diabetes mellitus by affecting the translocation of GLUT 4 transporter and lipid metabolism via Forkhead box protein O1 (FoxO1), mammalian target of rapamycin complex 1 (mTORC1), and sterol regulatory element-binding proteins (SREBPs) [24,28].