Figure 4.

Effect of MMP9 on LPS-induced expression of RANKL, RANK, OPG, and OCN. MC3T3-E1 cells were pre-treated with MMP9 overexpression plasmid or si-MMP9-3 (target sequences: GGAACTCACACGACATCTT) for 24 h. The 20 μg/ml of LPS was added to the culture medium for another 12 h. qRT-PCR and Western blot were performed to detect RANKL (a–c), RANK (d–f), OPG (g–i), and OCN (j–l) expressions. Quantification of protein expression was normalized to GAPDH using a densitometer (imaging system). The data are representative of three independent experiments and expressed as the mean ± SD. *P < 0.05 vs. LPS; **P < 0.01 vs. LPS.