C1GALT1 and breast cancer: At the molecular level, manipulating the expression of C1GALT1 has been demonstrated to regulate O-glycosylation of MET in hepatocellular carcinoma, FGFR2 in colorectal cancer, Mucin 1 in breast cancer, EGFR in head and neck squamous cell carcinoma cells, and EPHA2 in gastric cancer, respectively, and affects cancer malignant behaviors [23, 24, 26–28].