NCAM1 and nonpapillary renal cell carcinoma: To investigate the function of PSA-CD56 in the malignant phenotypes of ccRCC cells, CCK-8 and colony formation assays showed that overexpression of CD56 promoted the proliferation and colony formation ability of Caki-1 cells, but there was no obvious difference between the CD56-N459,488Q-OE and control groups (Fig. 5A, B).