Figure 4.

Effect of EGCG on BMP-4-induced phosphorylation of Smad1 in MC3T3-E1 cells. Cultured cells were pretreated with the indicated doses of EGCG for 60 min, then stimulated with 30 ng/ml BMP-4 or vehicle for 45 min. Cell extracts were then subjected to SDS-PAGE and subsequent western blot analysis using primary antibodies against phospho-Smad1 and GAPDH. The bar chart shows the levels of BMP-4-induced phosphorylation determined by laser-based densitometric analysis. 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. N.S., no significant difference; EGCG, (−)-epigallocatechin gallate; BMP-4, bone morphogenic protein-4; phospho, phosphorylated.