Cells were pretreated with indicated concentrations of Tβ4 peptide for 2 hours, post-incubated with 200 μM H2O2 for 48 hours, and then conditioned medium (CM) was collected. Mouse BMMs were cultured with CM in the presence of M-CSF (30 ng/mL) and RANKL (100 ng/mL), as described in Materials and methods. After 5 days, cells were fixed and stained for TRAP as a marker of osteoclasts (A), and the number of TRAP-positive multinucleated cells (MNCs) was scored (B). TRAP osteoclast activity was assayed using the TRAP cytochemical stain technique (C). * Statistically significant differences compared with the control, p<0.05. The data presented were representative of three independent experiments.