BCKDK and obesity due to melanocortin 4 receptor deficiency: In livers of HCC patients, and animal models, including high-fat diet-induced obesity and HCC tumor models, BCKDH activity and expression were found to be downregulated, and BCKDH kinase (BCKDK), the enzyme responsible for suppressing the activity of BCKDH, was found to be upregulated [23].