FGF23 and chronic kidney disease: In valvular calcification (mitral valve and aortic valve) associated with CKD, an upregulation of FGF23 in the heart and vascular tissues was observed selectively in S100 transgenic mice with CKD but not in CKD wild-type or CKD Ager null S100 transgenic mice, thereby implicating S100/RAGE in upregulation of FGF23 and pro-inflammatory factors contributing to vascular calcification (62).