Elevated apoptosis in atypical adenomatous hyperplasia lesions from lungs of <i>Rb1</i>^∆L/∆L mice expressing KrasG12D.

<p>Six to eight week old LSL-<i>Kras; Rb1</i>^<i>+/+</i> and LSL-<i>Kras; Rb1</i>^∆L/∆L mice were infected intra-nasally with Ad-Cre to activate the oncogenic KrasG12D. Characteristics of lung tumors at six and 12 weeks post Ad-Cre infection were assessed. (<b>A</b>) Quantitation of Ki67 positive cells in the adenomas from LSL-<i>Kras; Rb1</i>^<i>+/+</i> and LSL-<i>Kras; Rb1</i>^∆L/∆L lungs at the indicated time points. (<b>B</b>) Senescence associated β-galactosidase staining of cryo-sections from LSL-<i>Kras; Rb1</i>^<i>+/+</i> and LSL-<i>Kras; Rb1</i>^∆L/∆L lungs at the indicated time points. Sections were counterstained with haematoxylin. Scale bars are 50 µm. (<b>C</b>) Representative TUNEL stained lung sections from LSL-<i>Kras; Rb1</i>^<i>+/+</i> and LSL-<i>Kras; Rb1</i>^∆L/∆L mice 12 weeks following Ad-Cre infection. DAPI was used to counterstain the nuclei. Arrowheads indicate a selection of TUNEL positive nuclei. (<b>D</b>) Representative TUNEL stained lung sections six weeks following Ad-Cre infection. DAPI was used to stain the nuclei. (<b>E</b>) Quantitation of TUNEL positive cells in B that are associated with atypical adenomatous hyperplasia lesions in LSL-<i>Kras; Rb1</i>^<i>+/+</i> and LSL-<i>Kras; Rb1</i>^{<i>∆L/∆L</i>} lungs. Means were compared by a t-test, statistically significant differences are shown by an asterisk (p=0.001). Scale bars are 50 µm.