CDKN2B and glioblastoma: CDKN2B deletions have been previously identified to track most tightly with the mesenchymal and classical/astrocytic subtypes of GBM, and indeed, at the single cell level, loss of expression was found to dominate the astrocytic and mesenchymal cell clusters, while any remaining expression was limited to neural progenitor cells (NPC) and, to a lesser extent, to OPC clusters of cells (Figure 2A).