EPOR and chronic kidney disease: As the mesenchymal cells (including osteocytes), and not the B cells, are the main producers of RANKL 50 and osteoblasts are the main source of OPG 51, we expect that the observed decrease in RANKL mRNA is not primarily due to an alteration in their expression by BM B cells with EPO-R cKD, but rather to an indirect effect of the EPO-R cKD on the main producers of these key molecules.