However, no significant difference in transcriptional levels of proteoglycan core proteins e. g. syndecans and glypicans, or glycosaminoglycan biosynthetic enzymes e. g. the synthases Chsy-1 and -3 as well as the different sulfotransferases (Chst1 up to Chst15) and the C-5 epimerases Dse and Dsel, or most MMPs were found when we selectively compared their expression level in SG+/- and SG-/- mammary tumours. This evidence concerns the gene CHST15 and breast cancer.