NCAM1 and cancer: In summary, results from our current NMR studies, and previous findings on the DP of polySia chains and the cooperative interactions between PSTD-CMP-Sia, PSTD-polySia, PBR-NCAM, and PBR-PSTD [26,27,28,29,30,63,78] now provide greater insight into key molecular processes regulating the importance of these interactions in modulating NCAM polysialylation, which underlie many of the neuronal and immune system development and cancer metastatic events in human health and disease.