CD44 and glioblastoma: To investigate the role of GSC-secretedbiomolecules in glioblastoma heterogeneity and cell plasticity, proneural(NCH421k, NCH644, NCH441) and mesenchymal (NCH705, NCH711d) patient-derivedglioblastoma stem-like cells were used, which were classified intosubtypes with single-sample gene set enrichment analysis (ssGSEA)17 using the Wang gene signatures.5 In this regard, proneural cells were treated with the conditionedmedium from mesenchymal cells, and the abundance of CD44, a well-characterizedmesenchymal GSC marker, was measured by flow cytometry.