CHI3L1 and glioblastoma: The PDGFRA-cocluster showed high expression of GRIA2, OLIG2, and NCAM1/2 as well as other genes which are signatures of the “Proneural” transcriptomal class of GBM previously described.[19] Conversely, signature genes of the “Mesenchymal” GBM class such as YKL40/CHI3L1, IGFBP2 and VEGFA were most highly expressed in the NF1-cocluster transcriptomal group (Figure S5).