VWF and glioblastoma: On double-label analysis of human GBM tissue arrays (US Biomax, Inc., GL805a, GL805b and BS17017a) for the integrin α3 subunit and vwf, we found the mean fluorescence intensity of the integrin α3 subunit on vwf-positive pixels was significantly higher in GBM tumors as compared to normal brain (Fig. 2h).