ST6GAL1 and melanoma: Glycosylation is one of the most recurrent PTMs in melanoma, with GnT-III, GnT-V, ST3GAL1, ST6GAL1 and FUT8 as the most aberrantly expressed glycosyltransferases, and integrins, epidermal growth factor receptor (EGFR), cell adhesion molecule L1 (L1CAM) and the receptor tyrosine kinase AXL among the main glycosylated substrates [15].