IL6 and renal cell carcinoma: Using three different renal cell carcinoma cell lines, one group showed that treatment of cells in vitro and in vivo inhibited tumor growth through a possible mechanism involving inhibition of NF-kB and expression of its downstream products interleukin-6 (IL-6), interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) [40].