Interestingly, the calcein release assay (Figures 2(i)–2(l)), perforin polarization assay (Figures 2(m)–2(p)), and conjugation assay (Figures 2(q)–2(t)) revealed that circFOXO3 overexpression significantly promoted cell death, whereas circFOXO3 downregulation markedly inhibited cell death, indicating that circFOXO3 aggravates the cytotoxic activity of NK cells to ccRCC cells. This evidence concerns the gene PRF1 and nonpapillary renal cell carcinoma.