Inhibitory effect of NDGA on osteoclastogenesis is not attributed to the inhibition of lipoxygenase. (a–c) Treatment with the 5-LO metabolites does not cancel the inhibitory effect of NDGA on osteoclast differentiation. RAW-D cells were treated with NDGA for 60 min, and then treated with 5(S)-HETE (a), LTB4 (b), and LTC4 (c) as indicated. The cells were cultured for 3 days for forming osteoclast-like MNCs. TRAP-positive MNCs were counted. (d) Effect of REV-5901 and baicalein on osteoclast formation. RAW-D cells were cultured for 3 days for forming osteoclast-like MNCs in the presence of the indicated concentrations of REV-5901 (left panel) or baicalein (right panel). TRAP-positive MNCs were counted. Results are presented as means±s.d. (n=4). Data were analyzed by Student’ s t-test. ***P<0.001 compared with the culture without NDGA.