MKI67 and neoplasm: In order to compare proliferation, Ki67 staining was performed, showing a significant increase in Ki67‐positive nuclei for relapsed (n = 25) in comparison to ependymoma primary tumor samples (n = 14) (Figure 1B,D,F,H,J,L,N,P,T, 11.62 ± 2.83 [mean ± SEM] for primary tumors vs. 26.05 ± 3.16 [mean ± SEM] for relapsed tumors, P = 0.0042 [t‐test]).