Foxm1 in Lung Tumors Figure 3. Lung tumors are originated from type II lung epithelial cells. Lungs from epFoxm12/2 and control Foxm1fl/fl mice, that were given Dox in water starting 4 weeks before urethane injections, were photographed and fixed 28 weeks after the first urethane injection. Lung sections were used either for H&E staining or immunohistochemistry. A. Photographs of control Foxm1fl/fl mouse lungs (left lungs) depict lung tumors 28 weeks after the first urethane injection. Experimental epFoxm12/2 mice were resistant to tumor induction (right lungs), showing no visible tumors. B. H&E staining demonstrates a reduction in the size of lung tumors (Tu) in epFoxm12/2 mouse lungs. C. Lung tumors in control and epFoxm12/2 are positive for SPC, a marker of type II lung epithelial cells. D. Lung tumors in control and epFoxm12/2 are negative for CCSP, a marker of Clara cells. E. Similar expression of TTF-1 transcription factor in epFoxm12/2 and control Foxm1fl/fl tumors. Magnification: A panels, 106; B–E panels, 1006. doi:10.1371/journal.pone.0006609.g003 PLoS ONE | www.plosone.org 5 August 2009 | Volume 4 | Issue 8 | e6609