IDH1 and glioma: In addition to GAFP, several proteins that are potentially important in gliomas are myelin basic protein, vascular endothelial growth factor, YKL-40, matrix metallopeptidase-9, interleukin 6, 2-hydroxyglutarate (2-HG) (as a surrogate of IDH mutations), histidine, and tryptophan (117, 118).