Fig. 2. Rb ablation results in epithelial abnormalities. (A-L) Morphological examination, TUNEL analysis and immunohistochemisty for Ki67 and PCNA in lungs from day 1 pups after Rb ablation (CC10-rtTA), from genetically identical pups without doxycycline treatment (No Dox), and from pups lacking one or both transgenes (Control). Arrows mark apoptotic cells (A), TUNEL-positive cells (D,E) and scattered PCNA-positive cells (K,L). Abbreviations are as in Fig. 1. (M) Quantification of epithelial apoptosis and proliferation as assessed by the percentage of TUNEL-positive and Ki67-positive cells, respectively. Rb ablation results in statistically significant increases in epithelial apoptosis and proliferation (^*P<0.0002). Data represents the analysis of seven CC10-rtTA, eight control and four No Dox mice.