High ST6GanNAc2 in estrogen receptor (ER)-positive breast cancers reduces galectin-3 binding and metastasis by increasing the sialylation of core 1 antigen, whereas low ST6GanNAc2 in ER-negative breast cancers shows high endothelial cell adhesion and metastasis via galectin-3 binding [91]. This evidence concerns the gene ESR1 and breast cancer.