Next, using western blotting, we found that RAP1B protein was highly expressed in another 16 paired RCC tissues and adjacent non-tumorous tissues (4 pairs were remained from the 33 paired samples and the other 12 pairs were newly collected) as well as three tested human renal carcinoma cell lines, including A498, ACHN and Caki-1, compared with HK-2 cells (Supplementary Figure S1A, S1B and Figure 2F), while no significant difference in the expression levels of RAP1B mRNA was observed between the RCC tissue samples and the corresponding adjacent non-tumorous samples (Supplementary Figure S1C). This evidence concerns the gene RAP1B and renal cell carcinoma.