Fig. 2. Inhibition of PERK suppresses osteoclast differentiation and bone resorption.

a–d BMMs were treated with PERK siRNA or small molecule inhibitor GSK2606414 (0.01, 0.05, 0.1 μM) in the presence of RANKL (100 ng/mL) and M-CSF (30 ng/mL) for 4 days. Then, TRAP assay was performed. TRAP-positive multinucleated osteoclasts (≥3 nuclei) were counted. e–h BMMs were seeded in Osteo Aaasy Surface plate at a density of 2 × 10⁴ cells/well, and cultured with 100 ng/mL RANKL and 30 ng/mL M-CSF. After mature osteoclasts were formed in each group, PERK siRNA and GSK2606414 were applied for 3 days. Bone resorption area was quantified by using Image J, Scale bar = 400 μm. Data are presented as means ± SD of 3 independent experiments; **p < 0.01.