RPLP0 and nonpapillary renal cell carcinoma: Different pattern occurs for RG pair selection, since only RPL13 + RPLP0 selected by the GeNorm algorithm (Table 5) fulfils statistical criteria; therefore, for matched tumor-control-metastasized ccRCC samples (group IV) RPL13 + RPLP0 pair may be considered for normalization in gene expression studies.