One small-molecule STAT3 inhibitor, AG490, was originally selected from a group of tyrphostins screened for their ability to block Jak2 activity and has been shown to inhibit growth and induce apoptosis in some types of cancer cells, including renal cancer cells (Meydan et al, 1996; Horiguchi et al, 2002a). Here, STAT3 is linked to renal carcinoma.