PSMB2 and nonpapillary renal cell carcinoma: Finally, results from our study showed that higher mRNA expressions of PSMB1/2/4/7/8/9/10 were found in ccRCC tissues compared to normal tissues, transcriptional levels of PSMB2/3/4/6/8/9/10 were significantly positively related with patients' individual cancer stages and grades.