NES and obesity due to melanocortin 4 receptor deficiency: In both crosses, the homozygous LSL-PrRP littermates show divergent body weights at 8 to 9 weeks of age on normal chow when compared with the wild-type and the Cre-expressing mice; however, the obesity is fully reversed in the nestin-Cre::LSL-PrRP and TH-Cre::LSL-PrRP mice (Figures 6A and 6B).