Cell proliferation in tumor tissues was analyzed by counting anti-Ki-67 antibody positive cells in wild type (A) and in AT
-KO mice (B). Quantitative analysis of cell proliferation (C) was carried out by counting anti-Ki-67 antibody positive and negative cells in five random view fields; mean % positive cells was calculated from this raw data for graphical presentation. Data are presented as percentages ± SEM of Ki-67 positive cells/field. Original magnification of each panel is 400 ×. * P ≤ 0.001 as compared to the level of wild type mouse group.