NCAM1 and metastatic neoplasm: One of the latest advances in research on PTMs is the inhibition of the polysialylation of neuronal cell adhesion molecule (NCAM) [17,18], which is strongly related to the migration and invasion of tumor cells and is associated with aggressive, metastatic disease and poor clinical prognosis in the clinic due to the formation of polysialic acid (poly-Sia) on the surface of NCAM [19,20,21,22].