Fig. 4.

E₂ attenuates BMP-2-induced osteoblast differentiation and target gene expression. (A) Alkaline phosphatase activity in 2T3 and C2C12 cells incubated with vehicle or the indicated doses of BMP-2 in the presence of E₂ (10⁻⁸ M) for 1, 3, and 5 days. (B) Osteocalcin levels in the culture medium of C2C12 cells treated as described earlier for 3 and 5 days. (C) Smad6 mRNA levels determined by quantitative RT-PCR in C2C12 cells treated as described earlier for 3 days or (D) in U2OS cells pretreated with vehicle or E₂ (10⁻⁷ M) for 1 hour and treated with or without BMP-2 (100 ng/mL) for 2 hours in the presence (left panel) or absence (right panel) of doxycycline. *p < .05 versus BMP-2.