sVEGFR2 and sTNFR1 are both soluble receptors; sVEGFR2 binds free circulating VEGF in the blood and is a potent inhibitor of angiogenesis (31, 32) and sTNFR1 is the soluble form of tumor necrosis factor receptor 1, which is believed to regulate tumor necrosis factor alpha (TNF-α) signaling by binding free TNF-α in the blood (33)