GPC1 and glioblastoma: Important results are obtained from the experiments with TMZ-resistant GBM cells, which allow us to identify potential resistance-related PGs: glypican-1–silenced U-251 cells were much more susceptible to TMZ than intact U-251 MG cells (35); high expression of decorin and lumican in GBM and neuroblastoma stem cells are associated with TMZ resistance (36); CSPG4 is related in molecular mechanisms of TMZ resistance of GBM cells (37); experimental degradation of CS by chondroitinase ABC sensitizes glioblastoma cells to TMZ (38).