CREG1 and nonpapillary renal cell carcinoma: Among the candidate genes derived from the pan-cancer analysis (CREG1, NME2, and TSPYL5), NME2 was prioritized for functional validation based on the following rationale: its significant overexpression and prognostic value in ccRCC, its high frequency of copy number variations across cancers, and most importantly, the compelling biological plausibility that its known role in nucleotide metabolism could directly underpin the enhanced oxidative phosphorylation phenotype observed in high-SRSM tumors.