MMP9 and nonpapillary renal cell carcinoma: The riskscore of each ccRCC case was calculated using the following formula: Riskscore = (−0.0454)*DYSF + (0.0576)*MMP9 + (−0.0536)*SLC22A4 + (−0.1269)*SELP + (-0.1586)*KCNJ15 + (0.0513)*G0S2.