ST6GalNAc-I (N-acetylgalactosaminide α2,6-sialyltransferase 1) is an O-glycosyltransferase, which conjugates sialic acid with an α2,6 linkage to N-acetylgalactosamine (GalNAc) glycans, generating the tumor-related STn antigen (6, 11, 12). This evidence concerns the gene ST6GALNAC1 and neoplasm.