CHI3L1 and glioblastoma: The identification of elevated BIRC3 mRNA and protein as a defining feature of mesenchymal GBM marker is novel and, interestingly, our analyses indicate that it is an independent biomarker of this subtype, as it does not correlate with alterations in the expression of NF-1, and other genes such as CASP1/4/5/8, ILR4, CHI3L1, TRADD, TLR2/4, and RELB10 that have been associated with mesenchymal GBM.