We observed that eight proximal tubule-specific proteins (GGT1, BHMT, LRP2, DPYS, AGMAT, SLC22A8, SLC22A13, and HRSP12), annotated by the HPA database42, were significantly downregulated in tumor tissues (Supplementary Fig. 4b), revealing the loss of tissue identity of ccRCC tumors. This evidence concerns the gene GGT1 and nonpapillary renal cell carcinoma.