Figure 1. Development of lung tumors in LSL–K-ras^G12D;Fap^+/+, LSL–K-ras^G12D;Fap^+/LacZ, and LSL–K-ras^G12D;Fap^LacZ/LacZ mice.

(A) Representative sections from each genotype at 8 weeks after Ad-Cre infection. Regions of hyperplasia (asterisks) and adenomas (pound symbols) are indicated. Original magnification, ×4 (top row); ×40 (bottom 2 rows). Scale bar: 100 μm. Images that display areas of Ki67 staining, shown in the bottom row of panels, were selected based on similarity of tumor content (indicated by solid lines) between genotypes, whereas H&E-stained sections show randomly selected representative areas, unrelated to those shown for Ki67. (B) Tumor-to-lung area (T/L) ratio in LSL–K-ras^G12D;Fap^+/+, LSL–K-ras^G12D;Fap^+/LacZ, and LSL–K-ras^G12D;Fap^LacZ/LacZ mice at 8 weeks after Ad-Cre infection (n = 11) and proliferative index, which is calculated as percentage of Ki67-positive cells in the indicated number of animals for each genotype (n = 5 animals). Results are expressed as mean ± SEM.