ST6GAL1 and neoplasm: Through the α2,6 sialylation of receptors — such as the β1 integrin (15, 16), the Fas and TNF receptor 1 (TNFR1) death receptors (17, 18), and the receptor tyrosine kinases, epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor (also known as MET), and human epidermal growth factor receptor 2 (HER2/erbB2) (19–24) — ST6GAL1 promotes tumor cell migration and invasion, apoptosis resistance, and epithelial-mesenchymal transition (EMT).