PSMB2 and nonpapillary renal cell carcinoma: As was shown in Figure 2, mRNA expressions of PSMB1, PSMB2, PSMB4, PSMB7-10 were found to be significantly elevated in ccRCC tissues compared to normal samples while mRNA expressions of PSMB5, PSMB6 were significantly lower, no statistically difference being observed between cancer tissues and normal tissues with regards to PSMB3.