NLGN1 and nonpapillary renal cell carcinoma: To test this hypothesis, we first concomitantly over-expressed FZD4 in NLGN1-AS1 knockdown ccRCC cells, we first verified the expression efficiency of FZD4 by qRT-PCR analysis in 769-P and Caki-1 cells of different transfected groups (Figure 7A).