FOXP3 and nonpapillary renal cell carcinoma: For the FoxP3 loss-of-function in vivo experiment, the 786-O cell line was selected in our study, because (1) 786-O is established as one of the first ccRCC cell lines and it has many characteristics of ccRCC; meanwhile, ccRCC is the most dominated pathological type among all RCC cases; (2) compared to other RCC cell lines, there was a higher expression level of FoxP3 in the 786-O cell line; and (3) SETD2 mutation could also be detected in the 786-O cell line.