Extensive metabolic hepatic metabolism of mometasone furoate to multiple metabolites occurs. Risperidone undergoes hepatic metabolism and renal excretion. Glucose-6-phosphatase is one of the key liver enzymes involved in regulating sugar metabolism. Protein kinase A acts to phosphorylate many enzymes important in metabolism. Such a mechanism depends on factors that influence the metabolism and excretion of hormones. Knockout of the NF1 gene in muscle results in deregulated lipid metabolism and muscle weakness. Due to lack of oxygen, cellular respiration diminishes and anaerobic metabolism predominates. Digestion breaks the proteins down for use in the metabolism. Research has been able to show the function of niacin in the pathway lipid metabolism. The end-product of catabolism of protein metabolism in animals is nitrogen. APOE was initially recognized for its importance in lipoprotein metabolism and cardiovascular disease. Oxygen is required for normal cell metabolism. The predominant enzyme responsible for metabolism of tacrolimus is CYP3A5. They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. Restoring NAD levels is essential to the continuation of anaerobic energy metabolism through glycolysis.