KDR and nonpapillary renal cell carcinoma: We also documented that increased expression of the proteasome components PSMB1 and PSMB3 confer resistance to VEGFR-TKI therapy in stage IV ccRCC, and previous studies have reported that overexpression of PSMB1/2/3/4/6/8/9/10 was associated with worse ccRCC prognosis (23).