(A) FVB mice were subjected to 10 Gy delivered to the thorax (left) or pelvis (right). Blood was collected 24 hours later, and plasma TGF-β1 level was measured as described in Methods. (B) Eight-week-old tumor-bearing MMTV/PyVmT mice or nontransgenic FVB mice bearing PyVmT tumors of 200 mm³ or greater in mammary fat pad no. 4 were left untreated or administered 10 Gy to the thorax. Plasma TGF-β1 levels were measured 24 hours later. (C) Transgenic mice were treated 3 times with vehicle or doxorubicin (5 mg/kg i.p.) at 21-day intervals starting at week 8. TGF-β1 was measured in plasma collected at week 15. Data in A–C represent 3 independent experiments using 3 subjects per group. (D) FVB mice were administered 10 Gy to the thorax. Five weeks later, lungs from irradiated mice and controls were harvested and lysates (250 μg/ml) added in triplicate wells to mink lung epithelial cells that stably express a plasminogen activator inhibitor–1/luciferase reporter (PAI-1/luciferase reporter). After 24 hours, luciferase expression was measured as described in Methods. *P < 0.05, **P < 0.01, ***P < 0.001 versus control.