Figure 4.

1α,25(OH)₂D₃ fails to inhibit NF-κB and p38/JNK pathways in osteoclast precursor cells. Osteoclast precursor cells were isolated from the bone marrow of C57BL/6J mice as M-CSF–dependent adherent cells and were treated with RANKL (40 ng/ml) for 24 hours in the absence or presence of 10^–8 M 1α,25(OH)₂D₃. Expression of RANK, p65, p52, and c-Jun proteins (A) and phosphorylation of IκB (IκB-p), p38 (p38-p), and JNK (JNK-p) (B) were analyzed by Western blotting after RANKL treatment for 15 minutes. β-Actin protein served as a loading control.