PROM1 and cancer: We identified peri-arteriolar GSC niches in sections of GBM samples based on immunohistochemical localization of cancer stem cell marker CD133, smooth muscle actin (SMA) as smooth muscle cell marker and cytokine SDF-1α, which have been shown to be associated with GSC niches (Hira et al. 2015, 2018b) (Fig. 3).