CNR1 and diabetic kidney disease: In accordance with renal hypoxia being a common feature of DKD [69,70], and the fact that HIF-1α promotes renal EPO synthesis in the RPTCs in diabetic humans and animals [71,72,73], we found a significant upregulation in renal EPO expression levels in diabetic WT animals that was completely absent in the RPTC-CB1−/− mice.