MC4R and obesity disorder: While the G protein-coupled receptor (GPCR), melanocortin-4 receptor (MC4R), is known to play a critical role in regulating energy homeostasis (Stutzmann et al. 2008, Wade et al. 2021), no safe anti-obesity drugs currently target MC4R (Tao 2009, Montero-Melendez et al. 2022).