Figure 9.

Effects of cytokines and growth factors on expression of vascular endothelial growth factor receptors (VEGFRs). The mRNA expression of the VEGFRs was examined by RT-PCR at 30 cycles as described in Materials and methods. (a) The expression of VEGFR-1, VEGFR-2 and neuropilin-1 in rheumatoid arthritis (RA) synovial fibroblasts (SFs) of different passages and human umbilical vein endothelial cells (HUVECs). Lanes 1 to 5 correspond to RA SFs of passages 5, 6, 7, 8 and 9, respectively. (b) The mRNA expression of VEGFR-1, VEGFR-2 and neuropilin-1 in RA SFs after 24 h stimulation with tumor necrosis factor (TNF)-α (0, 0.1, 1, 10 and 50 ng/ml), IL-1α (0, 0.1, 1, 10 and 50 ng/ml) or transforming growth factor (TGF)-β (0, 0.01, 0.1, 1 and 10 ng/ml). Note that TNF-α selectively induces the mRNA expression of VEGFR-2 in RA SFs.