NES and neoplasm: Figure 1Dc shows that CD34− cell-lined tubular structures were nestin-positive and contained red blood cells (Fig. 1Dc, red arrow). In addition, PAS-positive tubular structures containing red blood cells were lined by nestin positive cells in the luminal surface (Fig. 1Dd, black arrow). The interface of tumor cell-lined vessels and EC-lined vessels was also found in human GBM sections (Fig. 1E), with some tubular structures formed by both tumor cells (red arrow, brown color) and ECs (black arrow, black color).