Obesity causes increased circulating levels of insulin and insulin-like growth factors 1 and 2 which can bind insulin receptors, leading to downstream activation of RAS/MEK/MAPK and PI3K/Akt/mTOR pathways which upregulate S6K1, ultimately promoting protein and lipid biosynthesis supportive of dysregulated cell proliferation under conditions of excessive activation [93]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.