MKI67 and neoplasm: HGG xenograft and infiltrating tumor cells expressed a modest level of EGFR (staining index: 34.2 ± 1.9%, P = 7.49 × 10–15), Supplementary Fig. S2, and were highly proliferative (Ki-67 staining index: 66.3 ± 2.5%, P = 1.28 × 10–15) compared to surrounding normal brain (staining index: 3.6 ± 0.8% and 7.1 ± 1.3% and for EGFR and Ki-67, respectively), Fig. 4A,B.