Nine of the 31 proteins (ALDH3B1, CSTB, GNAI2, IST1, KRT19, RPS2, RPL7A, RPL18, RPL28; FC ≥ 2 in GBM Pre-OP relative to HC, adjusted p-val≤0.05) showed excellent diagnostic sensitivity and specificity on receiver operating characteristic (ROC) analysis (area-under-the ROC curve, AUC > 0.9; Fig. 2d) and improved the separation of Pre-OP GBM and HC specimens in a principal component analysis compared to the 1545 shared proteins (Fig. 2e-1, e-2). This evidence concerns the gene RPL18 and glioblastoma.