CPNE1 and nonpapillary renal cell carcinoma: Compared with HK-2 cell, the protein and mRNA expression level of CPNE1 in 786-O, OS-RC-2, ACHN and A-498 was generally upregulated, which suggested the expression level of CPNE1 in ccRCC cell lines was generally higher than that in renal epithelial cell (Figure 8A).