WWP1 and obesity due to melanocortin 4 receptor deficiency: Previously, we demonstrated that Wwp1 mRNA expression was upregulated in the obese Zucker fatty rat (fa/fa) compared with the Zucker lean rat (+/+) and that WWP1 mRNA and protein expression were increased in WAT derived from mice with high-fat diet (HFD)-induced obesity [35]; however, increases in Wwp1 mRNA expression levels in response to an HFD were not observed in the WAT of p53 knockout (KO) mice [35].