FUT4 and invasive ductal breast carcinoma: The high expression of FUT-3 and its product, tetrasaccharide Sialic Lewis x (sLex) has been observed in several kinds of malignant solid tumors, such as oral squamous cell carcinoma [14], breast invasive ductal carcinoma [15], pancreatic cancer [16], ovarian carcinoma and colorectal cancer [17].