FAS and obesity due to melanocortin 4 receptor deficiency: Our data from in vivo study confirmed that NR4A1 knockout (KO) mice fed with high‐fat diet were more prone to obesity, and gene expression levels of PPARγ and FAS were increased in KO mice compared to controls; our data from in vitro study showed that NR4A1 overexpression in 3T3‐L1 pre‐adipocytes inhibited adipogenesis.