NCAM1 and medulloblastoma: Embryonic human brain extract served as positive control since it is known to express high level of PSA-NCAM, as do medulloblastoma (MB) tissues [16], which was confirmed in the current study by immunohistochemistry (Figure 2C) and ELISA for MB (150-1030 pg PSA-NCAM/μg of protein, n = 3) and embryonic human brain (1600 pg PSA-NCAM/μg of protein).