Figure 2.

Knockdown CXCR4 by SiRNA CXCR4 decreased MMP-13 mRNA level. Chondrocytes were transfected with the pU6RNAi-CXCR4 siRNA or a control vector and then treated with SDF-1. Total RNA and protein were isolated for RT-PCR and Western blot, respectively. Transfection with siRNA against CXCR4 inhibited both CXCR4 mRNA and protein in comparison with the control samples without SiRNA CXCR4. (A) MMP-13 mRNA levels increased when SDF-1 was administered. Treatment with SiRNA CXCR4 before SDF-1 incubation eliminated the increase in MMP-13 mRNA. (B) Bar graphs show the averages of quantified data of MMP-13 mRNA from three independent experiments (n = 3). *P < 0.05 compared with control.