PCNA and colon adenoma: Tumors developed in both WT and Sesn2-/- mice displayed classical characteristics of colon adenomas, such as nuclear β-catenin staining (Figure 5H), increased cell proliferation (Figure 5I; PCNA staining), DNA damage (Figure 5J; γ-H2AX staining) and apoptotic cell death (Figure 5K; TUNEL staining).