CXCR4 and neoplasm: We found that, compared to unsorted control cells, CXCR4+/Lgr5-, Lgr5+/CXCR4- and Lgr5+/CXCR4+ cells generated tumors with significantly increased mass 8 weeks after transplantation; likewise, the Lgr5+/CXCR4+ cells generated the greatest tumor mass among all, based on bioluminescence examination, shown by representative images (Figure 3A), and by quantification (Figure 3B).