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). Here, CD34 is linked to neoplasm.