CTSK and chronic kidney disease: This study confirmed that CKD-WID markedly attenuated the expression of pro-osteoclastogenic genes and proteins c-Fos, cathepsin K, TRAP, and carbonic anhydrase II; decreased the expression of the Blimp1 gene and protein, a transcriptional regressor of anti-osteoclastogenic factor such as IRF-8; and enhanced dephosphorylation of NFATc1 by calcineurin.