Fibroblast grown factor 21 increases hepatic oxidative capacity but not physical activity or energy expenditure in hepatic peroxisome proliferator-activated receptor y coactivator-1a-deficient mice. Fletcher JA, Linden MA, Sheldon RD, Meers GM, Matthew Morris E, Butterfield A, Perfield II JW, Scott Rector R, Thyfault JP. Experimental Physiology. 11/28/2017.