Additional file 1: Fig. S1. Effects of ERN on osteoclast differentiation in RAW 264.7 cells. (A) Cell viability of ERN-treated RAW 264.7. RAW 264.7 cells were cultured in a 96-well plate and then treated with various concentrations of ERN for 4 days. Cell viability was assessed using CCK-8 assays. Cell viability was analyzed and expressed as a percentage of the value of ERN-untreated cells. (B) RAW 264.7 cells were treated with various concentrations of ERN followed by sRANKL for 4 days. The cells were then stained with TRAP. TRAP-positive multinuclear cells (≥ 3 nuclei) were counted. The rate of osteoclast formation was analyzed and expressed as a percentage of the values of sRANKL-only treated cells (C–H). mRNA expression levels of c-Fos, NFATc1, TRAP, Ctsk, DC-STAMP, and OC-STAMP were analyzed by real-time PCR and the results were normalized to the expression of β-actin-encoding ACTB. The data are expressed as the means ± SE of three independent experiments (n = 3). Means marked with different letters are significantly different (P