WT1 and nonpapillary renal cell carcinoma: Herein, lentiviral-based shRNA was used to directly knock-down WT1 in Caki-1 and 786-O cells, and we observed that depletion of WT1 induced an increase in NEDD4L promoter activity (Fig. 6G) and protein expression (Fig. 6H) in both cells, suggesting that WT1 might act as a transcriptional repressor induced by KSRP to transcriptionally suppress NEDD4L in ccRCC cells.