MKI67 and neoplasm: Metformin treatment (Figure 5I) was associated with a reduction in nuclear Ki-67 reactivity, compared to the controls (Figure 5H) (Ki-67 mean ± SEM: 55.1 ± 1.8 vs 74.8 ± 5.2 respectively; P < 0.02; 27% inhibition), suggesting an inhibitory effect of metformin on tumor proliferation.