MMP9 and systemic lupus erythematosus: To determine which chemokines produced by BMSCs mediated the effects of TNF-α, mRNA levels of matrix metalloproteinase 2 (MMP-2), MMP-9, C-X-C chemokine receptor type 4 (CXCR4), vascular endothelial growth factor (VEGF), VCAM-1, and HGF in BMSCs from SLE patients and normal controls were detected by RT-PCR, and only HGF mRNA level was decreased in SLE BMSCs (Figure 6(a)).