PTGS2 and nonpapillary renal cell carcinoma: A total of 19 differentially expressed FRGs was eventually determined, including 13 downregulated genes (MT1G, ACSF2, CHAC1, ACSL4, AKR1C2, PEBP1, PTGS2, AKR1C1, CBS, GOT1, ACO1, FDFT1, and HMGCR) and 6 upregulated genes (ALOX12, CD44, SLC7A11, ALOX5, HMOX1, and ALOX15B) in ccRCC tissues (Fig. 1A and B).