Accordingly, the sequence of leukocyte-derived N-CAM cDNA was found to be essentially identical with N-CAM cDNA from human neuroblastoma cells encoding the 140-kDa isoform of N-CAM [59], altogether indicating that CD56 on leukocytes corresponds to the 140 kDa NCAM transmembrane protein. This evidence concerns the gene NCAM1 and neuroblastoma.