PCNA and neoplasm: Immunostaining showed that berberine significantly decreased PCNA (44.60 ± 2.88 vs 65.80 ± 3.27, by 32%) and Ki-67 (6.73 ± 2.16 vs 14.89 ± 2.75, by 55%) positive cells (Figure 2A-B), suggesting that berberine inhibits tumor cell proliferation in Apcmin/+ mice.