NCAM1 and cancer: The expression of polysialic acid (polySia) on neuronal cell adhesion molecule (NCAM) [1,2,3,4,5,6,7] is called NCAM polysialylation, which is related to cancer cell migration through interactions between polysialyltransferases (polySTs) and CMP-Sia and polyST and polysialic acid (polySia) [8,9].