RUNX2 and nonpapillary renal cell carcinoma: To explore the function of Runx2 in ccRCC, two ccRCC cell lines CAKI-1 and SKRC39 with relative low expression of Runx2 were transfected with plasmid containing the coding sequence of Runx2, and overexpression of Runx2 was confirmed by qRT-PCR and western blot analyses (Fig. 2B).