The number of TRAP-positive multinucleated cells under stimulation with both RANKL and MSU was much higher than those stimulated with either RANKL or MSU crystals and markedly decreased in the cells treated with CKD-WID at doses of 0.5 and 1.0 μM, compared with cells without CKD-WID (Figure 3A). Here, ACP5 is linked to chronic kidney disease.