NCAM1 and nonpapillary renal cell carcinoma: In order to investigate the potential role of polysialylated CD56 in facilitating the malignant progression of ccRCC cells, we generated a mutated variant of CD56 by substituting asparagine (Asn, N) residues with glutamine (Gln, Q) at positions 459 and 488 (referred to as CD56-N459,488Q).