Activation of NF-κB in macrophages results in fewer lung metastases. IKFM or DNFM mice and controls were treated with doxycycline (dox; 2 g/L) for one week prior to PyVT cell injection. Dox treatment was continued until sacrifice at two weeks post-injection. (a) Lung tumor counts in IKFM and control mice (P = 0.0005; n = 11 control, n = 8 IKFM) and representative lung images. (b) Lung tumor counts in DNFM and control mice (P = 0.7997; n = 6 control, n = 8 DNFM). (c) IKFM mice were injected with PyVT cells. Dox treatment (2 g/L) began two days post injection and continued until sacrifice at two weeks post cells when surface lung tumors were counted (P = 0.9880; n = 7 control, n = 6 IKFM).