However, the fact that Ki67 values were clearly lower in AA than in GBM (mean of 12.13 + 8.96 for AA vs 22.27 + 16.63 for GBM) prevented us from drawing conclusions concerning the presence or absence of correlation between Ki67 and C-circle intensity in AA (Additional file 5: Table S4). Here, MKI67 is linked to glioblastoma.