Figure 4.

Regression of lung metastases following doxycycline withdrawal. Lung metastases (n = 7) arising in three independent MTB/TWNT mice were explanted onto the flanks of wild-type FVB/N hosts maintained on doxycycline. The primary mammary tumor presumed to be the source of each metastasis was grafted onto the contralateral flank of each host mouse. (A) The histology of H&E-stained sections derived from lung metastases closely resembled that of primary tumors, both in the case of in situ metastases (middle panel) and explanted metastases (right panel). (B) Similar rate and extent of regression for explants derived from primary mammary tumors and lung metastases. Regression curves for duplicate explants derived from a representative primary-metastasis pair.