HS6ST1 and central nervous system cancer: Expression of the main enzymes responsible for heparan sulfate biosynthesis and post-synthetic modification (EXT1, EXT2, NDST1, NDST2, GLCE, 2OST1/HS2ST1, 3OST1/HS3ST1, 3OST2/HS3ST2, 6OST1/HS6ST1, 6OST2/HS6ST2, SULF1, SULF2, HPSE) was determined in human gliomas of various degrees of malignancy (astrocytoma, Grade II, n = 9; anaplastic astrocytoma, Grades III, n = 5; glioblastoma, Grade IV, n = 28) by Real-Time RT-PCR (Figure 1).