VIM and neoplasm: To positively identify human GBM cells in mouse brains, we performed IHC with human specific antibodies against mitochondria (MT) and neurofilament vimentin that have been serially tested and validated in our previous reports [18, 20, 24, 27-29, 41] and detected the invasive cells, particularly those single cells that migrated deep into the normal mouse brains (Fig. 1b; Additional file 1: Fig. S1) together with tumor core cells.