DLEU1 knockdown inhibits the viability and clonogenic ability of RCC cells. si-DLEU1 was transfected into the KETR3 and 786-O RCC cells; scrambled siRNA was used as the NC. A total of 24 h post-transfection, DLEU1 expression in (A) KETR3 and (B) 786-O cells was determined via reverse transcription-quantitative PCR analysis. Post-transfection, cell viability was determined in (C) KETR3 and (D) 786-O cells via a Cell Counting Kit-8 assay. The colony formation ability of (E) KETR3 and (F) 786-O cells was determined using a colony formation assay. Data are presented as the means ± standard deviation (n=3). Results were obtained from three independent experiments. *P<0.05 vs. NC. DLEU1, deleted in lymphocytic leukemia 1; NC, negative control; OD, optical density; RCC, renal cell carcinoma; si/siRNA, small interfering RNA.