Effects of tumor necrosis factor-α, vascular endothelial growth factor165 and SU1498 on ADAM15 expression. (a) Effect of tumor necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF)165 on ADAM15 expression. After starvation, rheumatoid arthritis (RA) synovial fibroblasts (SFs) were treated with 10 ng/ml TNF-α and/or 40 ng/ml VEGF165 for 24 h, and then the expression of ADAM15, vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2 and neuropilin-1 was examined by RT-PCR at 25 cycles (ADAM15 and β-actin) or 30 cycles (VEGFR-1, VEGFR-2 and neuropilin-1) as described in Materials and methods. Note that treatment with TNF-α induces VEGFR-2 and co-treatment with TNF-α and VEGF165 stimulates the mRNA expression of ADAM15 in RA SFs. (b) Effect of SU1498 on ADAM15 expression. After starvation for 24 h, RA SFs were stimulated with 10 ng/ml TNF-α for 24 h to induce VEGFR-2. Then, the cells were treated with SU1498 (0, 1 and 10 μM) for 30 minutes and stimulated with 40 ng/ml VEGF165 for 24 h. The mRNA expression of ADAM15 was determined by RT-PCR at 25 cycles as described in Materials and methods. Note that the stimulated expression of ADAM15 mRNA is inhibited by the treatment with SU1498, while the expression of VEGFR-2 mRNA is not affected by the treatment.