To sum up the results from the gain- and loss-of-function studies of GPR151 in preadipocyte models, minimal but indispensable endogenous expression of GPR151 in adipose progenitor cells in generating lipid-rich adipocytes may underlie one of the mechanisms by which GPR151 promotes obesity. The gene discussed is GPR151; the disease is obesity due to melanocortin 4 receptor deficiency.