As shown in Figure 2C, ccRCC-derived cell line 786-O, A498, Caki-1, and Caki-2 had a drastic increase of E2F1 protein expression versus the normal renal proximal tubular cell line HKC, revealing metastatic ccRCC cell line Caki-1 the highest of all. The gene discussed is E2F1; the disease is nonpapillary renal cell carcinoma.