FGF21 and chronic kidney disease: In our mouse study, however, wild-type CKD mice showed greater pressor response and sympathetic activity during physical activity than Fgf21−/− CKD mice despite the fact that their vascular stiffness appeared comparable, because expression levels of markers for vascular calcification were not different between the wild-type CKD mice and the Fgf21−/− CKD mice.