Indeed, by performing stainings for SLUG with two well-known smooth muscle cells markers (PDGFRβ and αSMA) and two pan-endothelial markers (CD31 and VE-Cadherin) in two GBM samples, we established that around 50% of SLUG+ cells were vascular muscle cells, whereas very few expressed endothelial markers (Figure 4A,B). Here, PECAM1 is linked to glioblastoma.