To investigate the effects of Bcl-3 on the pulmonary metastasis of breastcancer in vivo, we depleted Bcl-3 in different breast cancer celllines using an inducible Tet-on lentivirus system.22 After infection with lentivirus, the cells wereexposed to doxycycline (Dox) (1 μg/ml) for more than4 days, and the expression of Bcl-3 was downregulated (Supplementary Figure 1c). This evidence concerns the gene BCL3 and breast cancer.