Since HAS2, CD44, and VEGF endogenous mRNA expression levels were very low in HRA cells although their expression levels were high in U373MG human astrocytoma cells [18] and SH-SY5Y human neuroblastoma cells [20], it was impossible to evaluate the effect of 4-MU treatment (data not shown). This evidence concerns the gene HAS2 and astrocytoma (excluding glioblastoma).