Chiao et al. demonstrated that CD133+ GSCs contributed to forming VM in tumor xenografts, particularly the CD133+ GSC-derived xenografts showed vessel-like structures negative for CD31 staining and positive for PAS and α-smooth muscle actin (α-SMA), suggesting that these cells may contribute to forming vessel-like structures by transdifferentiating in vascular smooth muscle-like cells. This evidence concerns the gene PECAM1 and neoplasm.