Apoptosis in tumor tissues was analyzed by visualizing TUNEL positive cells in wild type (A) and AT
-KO (B) mouse tumors. Quantitative analysis of apoptosis (C) was carried out by counting TUNEL 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 TUNEL positive cells/field. The original magnification of each panel is 400 ×.