Immunohistochemical detection of proliferating cell nuclear antigen on formalin-fixed, deparaffinized mouse liver and spleen sections. In the same experiments as those described in Figure 2, histopathologic sections of liver (A) and spleen (B) were stained with anti-PCNA antibody as described in “Materials and methods.” Images were observed under a microscope (original magnification × 40/0.75 NA PH2 objective lens). (C) PCNA-positive cell percentages are shown for liver (left) and spleen (right). Each column represents mean of 3 or 4 mice in an independent experiment; error bars represent SD. *P < .001, compared with other groups; #P < .05, compared with mice i, ii, and iv. Symbols i to v represent mice with the same treatment as in Figure 2.