NCAM1 and nonpapillary renal cell carcinoma: For the purpose of investigating the potential impact of polysialic acid modification on the malignant progression of ccRCC, we employed molecular cloning techniques to construct overexpression vectors for CD56 and CD56-N459,488Q and the latter mutated the asparagine (Asn, N) to glutamine (Gln, Q) at 459 and 488 sites of CD56 (Fig. 4A, lower).