Immunohistochemical detection and quantification of TGF-beta1 in lung at 16 weeks post –XRT. Mice on control diet (0% FLC) were exposed to a single fraction thoracic X-ray radiation therapy (13.5 Gy). Following XRT exposure, mice were switched to 10% FLC or 20% FLC diets that were initiated 24 hours post radiation exposure while control-fed mouse cohorts remained on 0% FLC diet throughout the course of the study. Lungs were harvested at 16 weeks post-XRT, paraffin embedded and immunostained for TGF beta1; brown staining (Panel A). Representative lung sections are shown In Panels a-b: representing 0% FLC, Panels c-d: representing 10% FLC and Panels e-f: representing 20% FLC. Sections were counterstained with methyl green. (Magnification 400X). Quantification of TGF-beta1 positivity (Panel B) was made using the Aperio image analysis system. #p<0.03 as compared to irradiated 0% FLC.