NTRK1 and obesity due to melanocortin 4 receptor deficiency: SEM3C has been known to transactivate multiple receptor tyrosine kinases and downstreams such as phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway, which is causally associated with obesity and glucose metabolism by promoting lipid biosynthesis and glucose uptake and by inhibiting lipolysis59.