EPO and calcification: One study reported that EPO attenuates vascular calcification by inhibiting endoplasmic reticulum stress in rats with CKD [40]; meanwhile, other studies have reported that EPO and HIF-1 can promote vascular calcification in CKD, suggesting that inappropriate use of EPO and prolyl HIF-hydroxylase (PH) enzyme (HIF-PH) inhibitors in CKD patients might aggravate vascular calcification and elicit adverse clinical consequences [41, 42].