DKK2 and nonpapillary renal cell carcinoma: Furthermore, the mRNA and protein levels of LZTFL1, SFRP1 and DKK2 were significantly down-regulated in miR-106b-5p overexpression ccRCC cells but up-regulated in miR-106b-5p-silenced cells as determined by qPCR and western blotting, respectively (Figure 5B, 5C).