C9 and glioblastoma: Moreover, when we analyzed the correlations between the concentrations of biomarker candidates in plasma and the total amounts of biomarker candidates in cytosol of GBM patients, Pearson correlation analysis showed significant positive correlations for CRP, C9, LRG1, and SERPINA3 (Table 5, S3 Fig), indicating the possibility that the concentrations of the biomarker candidates in GBM plasma reflect the amounts in the GBM tissues.