CXCR4 and teratoma: Consistent with the in vivo teratoma formation capacity, the cells in the EB could be differentiated into three germ lines in vitro, as demonstrated by the expression of ectoderm (ncam1 and notch), mesoderm (snai1 and snai2), and endoderm (β-catenin and cxcr4) genes (Figure 2).