Nevertheless, a newly developed cancer stem cell reporter vector system by the Wakefield group at NCI [33] may allow us to selectively label CSCs in vitro and in vivo in tumor xenografts and then to specifically examine in vivo evidence of the efficacy of TF-targeting therapies for eradication of CSCs in our ongoing studies using tumor cell line-derived and patient-derived xenograft mouse models. Here, TF is linked to cancer.