Fig. 1.

Interleukin (IL)-6 suppressed receptor activator of nuclear factor-κB ligand (RANKL)-induced differentiation of RAW cells into osteoclasts. RAW cells were cultured with soluble RANKL (sRANKL) (50 ng/ml) and various concentrations of IL-6 for 24 h. Cell lysate was collected from 24 h culture and the expression of mRNA for tartrate-resistant acid phosphatase isoform 5b (TRAP5b) and nuclear factor of activated T cells cytoplasmic 1 (NFATc1) was measured by real-time polymerase chain reaction (PCR) (a). RAW cells were cultured with sRANKL (50 ng/ml), IL-6 (100 ng/ml) and anti-IL-6R antibody (100 µg/ml) for 24 h or 3 days. Cell-free supernatant was collected and the concentration of TRAP5b was measured by enzyme-linked immunosorbent assay (b). Statistical significances were analysed by t-test (*: P < 0·05) or Dunnett's multiple comparison test (#P < 0·05).