CXCL8 and renal cell carcinoma: Circulating monocytes from patients and mice with renal cell carcinoma (RCC) display a pro-tumor gene signature with upregulated expression of pro-angiogenic factors interleukin 8 (IL-8) and vascular endothelial growth factor (VEGF), as well as matrix metalloproteinases (MPPs), including MMP19 and MMP10 [31].