Mouse BMMs (5 × 104 cells/well) were plated and cultured in α-MEM complete media containing M-CSF (30 ng/ml), sRANKL (10 ng/ml or 100 ng/ml), DPB-LPS (1 μg/ml), and/or EETC (10 μg/ml) for 7 days with replacement with fresh medium every second day. The cells were fixed with 4% paraformaldehyde for 10 min. Cells were reacted with the Acid Phosphatase, Leukocyte (TRAP) kit (Sigma-Aldrich) according to the manufacturer’s instruction. The number of TRAP-positive multinucleated cells (≥3 nuclei) were counted as osteoclasts per well. Reaction with only M-CSF was performed for control.