Figure 2.

Effect of EGCG on BMP-4-stimulated OPG release in MC3T3-E1 cells. (A) Cultured cells were pretreated with 30 µM EGCG (●, ○) or vehicle (▲, ∆) for 60 min, then stimulated with 30 ng/ml BMP-4 (●, ▲) or vehicle (○, ∆) for the indicated time periods. (B) Cultured cells were pretreated with the indicated doses of EGCG for 60 min, then stimulated with 30 ng/ml BMP-4 (●) or vehicle (○) for 48 h. Levels of osteoprotegerin in the culture medium were determined by ELISA. Data are presented as the mean ± standard error of the mean of three replicate experiments from three independent cell preparations. *P<0.05 vs. control cells and **P<0.05 vs. cells stimulated by BMP-4 and pretreated with vehicle. EGCG, (−)-epigallocatechin gallate; BMP-4, bone morphogenic protein-4; OPG, osteoprotegrin.