SIRT6 and nonpapillary renal cell carcinoma: Based on experiments (IHC) and data analysis, we speculated that the expression of SIRTs may be important for ccRCC, among them, SIRT4 and SIRT5 (particularly) could be involved in inhibiting the progression of ccRCC, whereas SIRT6 and SIRT7 are speculated to be important for promoting ccRCC development.