LEP and obesity due to melanocortin 4 receptor deficiency: Moreover, a review published in 2018 brought new insights into the role of the LEP/LEPRb axis in obesity-mediated cancers via the JAK/STAT, MAPK, and PI3K/AKT pathways, which are related to cell proliferation, cell migration and invasion, angiogenesis, vascular stimulation, and apoptosis.