AQP9 and nonpapillary renal cell carcinoma: Importantly, elevated AQP9 expression was significantly associated with poor PFS (TCGA: HR = 3.443, p = 0.040; FUSCC: HR = 1.714, p = 0.001) and poor OS (TCGA: HR = 1.714, p = 0.026; FUSCC: HR = 1.514, p = 0.026) in both cohorts of ccRCC patients.